feat: add video and audio picker buttons and upload support in Composer

- Add videoUri, audioUri, uploadedVideoUrl, uploadedAudioUrl, isUploadingMedia to ComposerUiState
- Add setVideo/removeVideo/setAudio/removeAudio methods to ComposerViewModel
- Update submitPost to upload video/audio via uploadMediaFile and pass URLs to MobiledocBuilder
- Save videoUri/audioUri to LocalPost for offline queue
- Add Video and Audio picker buttons to composer toolbar
- Add MediaPreviewCard composable showing filename, file size, and remove button
- Update PostUploadWorker to upload video/audio before building mobiledoc

app/src/main/java/com/swoosh/microblog/ui/composer/ComposerScreen.kt

@@ -110,8 +110,22 @@ fun ComposerScreen(
         }
     }
 
+    // Video picker
+    val videoPickerLauncher = rememberLauncherForActivityResult(
+        ActivityResultContracts.GetContent()
+    ) { uri: Uri? ->
+        uri?.let { viewModel.setVideo(it) }
+    }
+
+    // Audio picker
+    val audioPickerLauncher = rememberLauncherForActivityResult(
+        ActivityResultContracts.GetContent()
+    ) { uri: Uri? ->
+        uri?.let { viewModel.setAudio(it) }
+    }
+
     val canSubmit by remember {
-        derivedStateOf { !state.isSubmitting && (state.text.isNotBlank() || state.imageUris.isNotEmpty()) }
+        derivedStateOf { !state.isSubmitting && (state.text.isNotBlank() || state.imageUris.isNotEmpty() || state.videoUri != null || state.audioUri != null) }
     }
 
     Scaffold(
@@ -381,6 +395,12 @@ fun ComposerScreen(
                         OutlinedIconButton(onClick = { multiImagePickerLauncher.launch("image/*") }) {
                             Icon(Icons.Default.Image, "Attach images")
                         }
+                        OutlinedIconButton(onClick = { videoPickerLauncher.launch("video/*") }) {
+                            Icon(Icons.Default.Videocam, "Attach video")
+                        }
+                        OutlinedIconButton(onClick = { audioPickerLauncher.launch("audio/*") }) {
+                            Icon(Icons.Default.MusicNote, "Attach audio")
+                        }
                         OutlinedIconButton(onClick = { showLinkDialog = true }) {
                             Icon(Icons.Default.Link, "Add link")
                         }
@@ -433,6 +453,40 @@ fun ComposerScreen(
                         }
                     }
 
+                    // Video preview card
+                    AnimatedVisibility(
+                        visible = state.videoUri != null,
+                        enter = scaleIn(initialScale = 0f, animationSpec = SwooshMotion.bouncy()) + fadeIn(SwooshMotion.quick()),
+                        exit = scaleOut(animationSpec = SwooshMotion.quick()) + fadeOut(SwooshMotion.quick())
+                    ) {
+                        Column {
+                            Spacer(modifier = Modifier.height(12.dp))
+                            MediaPreviewCard(
+                                icon = Icons.Default.Videocam,
+                                label = "Video attached",
+                                uri = state.videoUri,
+                                onRemove = viewModel::removeVideo
+                            )
+                        }
+                    }
+
+                    // Audio preview card
+                    AnimatedVisibility(
+                        visible = state.audioUri != null,
+                        enter = scaleIn(initialScale = 0f, animationSpec = SwooshMotion.bouncy()) + fadeIn(SwooshMotion.quick()),
+                        exit = scaleOut(animationSpec = SwooshMotion.quick()) + fadeOut(SwooshMotion.quick())
+                    ) {
+                        Column {
+                            Spacer(modifier = Modifier.height(12.dp))
+                            MediaPreviewCard(
+                                icon = Icons.Default.MusicNote,
+                                label = "Audio attached",
+                                uri = state.audioUri,
+                                onRemove = viewModel::removeAudio
+                            )
+                        }
+                    }
+
                     // Link preview
                     AnimatedVisibility(
                         visible = state.isLoadingLink,
@@ -884,6 +938,95 @@ class HashtagVisualTransformation(private val hashtagColor: Color) : VisualTrans
     }
 }
 
+/**
+ * Compact preview card for attached video or audio files.
+ * Shows an icon, label, filename (from URI), and a remove button.
+ */
+@Composable
+fun MediaPreviewCard(
+    icon: androidx.compose.ui.graphics.vector.ImageVector,
+    label: String,
+    uri: Uri?,
+    onRemove: () -> Unit
+) {
+    val context = LocalContext.current
+    val fileName = remember(uri) {
+        uri?.let { mediaUri ->
+            try {
+                context.contentResolver.query(mediaUri, null, null, null, null)?.use { cursor ->
+                    val nameIndex = cursor.getColumnIndex(android.provider.OpenableColumns.DISPLAY_NAME)
+                    if (cursor.moveToFirst() && nameIndex >= 0) {
+                        cursor.getString(nameIndex)
+                    } else null
+                }
+            } catch (_: Exception) {
+                null
+            } ?: mediaUri.lastPathSegment ?: "Unknown file"
+        } ?: "Unknown file"
+    }
+
+    val fileSize = remember(uri) {
+        uri?.let { mediaUri ->
+            try {
+                context.contentResolver.query(mediaUri, null, null, null, null)?.use { cursor ->
+                    val sizeIndex = cursor.getColumnIndex(android.provider.OpenableColumns.SIZE)
+                    if (cursor.moveToFirst() && sizeIndex >= 0) {
+                        val bytes = cursor.getLong(sizeIndex)
+                        when {
+                            bytes < 1024 -> "$bytes B"
+                            bytes < 1024 * 1024 -> "${bytes / 1024} KB"
+                            else -> "%.1f MB".format(bytes / (1024.0 * 1024.0))
+                        }
+                    } else null
+                }
+            } catch (_: Exception) {
+                null
+            }
+        }
+    }
+
+    OutlinedCard(modifier = Modifier.fillMaxWidth()) {
+        Row(
+            modifier = Modifier
+                .fillMaxWidth()
+                .padding(12.dp),
+            verticalAlignment = Alignment.CenterVertically,
+            horizontalArrangement = Arrangement.SpaceBetween
+        ) {
+            Row(
+                verticalAlignment = Alignment.CenterVertically,
+                modifier = Modifier.weight(1f)
+            ) {
+                Icon(
+                    imageVector = icon,
+                    contentDescription = null,
+                    modifier = Modifier.size(24.dp),
+                    tint = MaterialTheme.colorScheme.primary
+                )
+                Spacer(modifier = Modifier.width(12.dp))
+                Column {
+                    Text(
+                        text = fileName,
+                        style = MaterialTheme.typography.bodyMedium,
+                        maxLines = 1,
+                        overflow = androidx.compose.ui.text.style.TextOverflow.Ellipsis
+                    )
+                    if (fileSize != null) {
+                        Text(
+                            text = fileSize,
+                            style = MaterialTheme.typography.labelSmall,
+                            color = MaterialTheme.colorScheme.onSurfaceVariant
+                        )
+                    }
+                }
+            }
+            IconButton(onClick = onRemove) {
+                Icon(Icons.Default.Close, "Remove $label", Modifier.size(18.dp))
+            }
+        }
+    }
+}
+
 /**
  * Tag input section with autocomplete suggestions and tag chips.
  */

app/src/main/java/com/swoosh/microblog/ui/composer/ComposerViewModel.kt

@@ -156,6 +156,22 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
         }
     }
 
+    fun setVideo(uri: Uri) {
+        _uiState.update { it.copy(videoUri = uri) }
+    }
+
+    fun removeVideo() {
+        _uiState.update { it.copy(videoUri = null, uploadedVideoUrl = null) }
+    }
+
+    fun setAudio(uri: Uri) {
+        _uiState.update { it.copy(audioUri = uri) }
+    }
+
+    fun removeAudio() {
+        _uiState.update { it.copy(audioUri = null, uploadedAudioUrl = null) }
+    }
+
     fun fetchLinkPreview(url: String) {
         if (url.isBlank()) return
         viewModelScope.launch {
@@ -234,7 +250,7 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
 
     private fun submitPost(status: PostStatus, offlineQueueStatus: QueueStatus) {
         val state = _uiState.value
-        if (state.text.isBlank() && state.imageUris.isEmpty()) return
+        if (state.text.isBlank() && state.imageUris.isEmpty() && state.videoUri == null && state.audioUri == null) return
 
         viewModelScope.launch {
             _uiState.update { it.copy(isSubmitting = true, error = null) }
@@ -259,6 +275,8 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
                     imageUri = state.imageUris.firstOrNull()?.toString(),
                     imageUris = Converters.stringListToJson(state.imageUris.map { it.toString() }),
                     imageAlt = altText,
+                    videoUri = state.videoUri?.toString(),
+                    audioUri = state.audioUri?.toString(),
                     linkUrl = state.linkPreview?.url,
                     linkTitle = state.linkPreview?.title,
                     linkDescription = state.linkPreview?.description,
@@ -290,12 +308,44 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
                 )
             }
 
+            // Upload video if present
+            var videoUrl: String? = state.uploadedVideoUrl
+            if (videoUrl == null && state.videoUri != null) {
+                _uiState.update { it.copy(isUploadingMedia = true) }
+                val videoResult = repository.uploadMediaFile(state.videoUri)
+                videoResult.fold(
+                    onSuccess = { url -> videoUrl = url },
+                    onFailure = { e ->
+                        _uiState.update { it.copy(isSubmitting = false, isUploadingMedia = false, error = "Video upload failed: ${e.message}") }
+                        return@launch
+                    }
+                )
+            }
+
+            // Upload audio if present
+            var audioUrl: String? = state.uploadedAudioUrl
+            if (audioUrl == null && state.audioUri != null) {
+                _uiState.update { it.copy(isUploadingMedia = true) }
+                val audioResult = repository.uploadMediaFile(state.audioUri)
+                audioResult.fold(
+                    onSuccess = { url -> audioUrl = url },
+                    onFailure = { e ->
+                        _uiState.update { it.copy(isSubmitting = false, isUploadingMedia = false, error = "Audio upload failed: ${e.message}") }
+                        return@launch
+                    }
+                )
+            }
+
+            _uiState.update { it.copy(isUploadingMedia = false) }
+
             val featureImage = uploadedImageUrls.firstOrNull()
 
             val mobiledoc = MobiledocBuilder.build(
                 state.text, uploadedImageUrls,
                 state.linkPreview?.url, state.linkPreview?.title, state.linkPreview?.description,
-                altText
+                altText,
+                videoUrl,
+                audioUrl
             )
             val ghostTags = allTags.map { GhostTag(name = it) }
 
@@ -336,6 +386,10 @@ class ComposerViewModel(application: Application) : AndroidViewModel(application
                         uploadedImageUrl = featureImage,
                         uploadedImageUrls = Converters.stringListToJson(uploadedImageUrls),
                         imageAlt = altText,
+                        videoUri = state.videoUri?.toString(),
+                        uploadedVideoUrl = videoUrl,
+                        audioUri = state.audioUri?.toString(),
+                        uploadedAudioUrl = audioUrl,
                         linkUrl = state.linkPreview?.url,
                         linkTitle = state.linkPreview?.title,
                         linkDescription = state.linkPreview?.description,
@@ -369,6 +423,11 @@ data class ComposerUiState(
     val text: String = "",
     val imageUris: List<Uri> = emptyList(),
     val imageAlt: String = "",
+    val videoUri: Uri? = null,
+    val audioUri: Uri? = null,
+    val uploadedVideoUrl: String? = null,
+    val uploadedAudioUrl: String? = null,
+    val isUploadingMedia: Boolean = false,
     val linkPreview: LinkPreview? = null,
     val isLoadingLink: Boolean = false,
     val scheduledAt: String? = null,

app/src/main/java/com/swoosh/microblog/worker/PostUploadWorker.kt

@@ -66,9 +66,35 @@ class PostUploadWorker(
                 featureImage = allImageUrls.first()
             }
 
+            // Upload video if needed
+            var videoUrl = post.uploadedVideoUrl
+            if (videoUrl == null && post.videoUri != null) {
+                val videoResult = repository.uploadMediaFile(Uri.parse(post.videoUri))
+                if (videoResult.isFailure) {
+                    repository.updateQueueStatus(post.localId, QueueStatus.FAILED)
+                    allSuccess = false
+                    continue
+                }
+                videoUrl = videoResult.getOrNull()
+            }
+
+            // Upload audio if needed
+            var audioUrl = post.uploadedAudioUrl
+            if (audioUrl == null && post.audioUri != null) {
+                val audioResult = repository.uploadMediaFile(Uri.parse(post.audioUri))
+                if (audioResult.isFailure) {
+                    repository.updateQueueStatus(post.localId, QueueStatus.FAILED)
+                    allSuccess = false
+                    continue
+                }
+                audioUrl = audioResult.getOrNull()
+            }
+
             val mobiledoc = MobiledocBuilder.build(
                 post.content, allImageUrls, post.linkUrl, post.linkTitle, post.linkDescription,
-                post.imageAlt
+                post.imageAlt,
+                videoUrl,
+                audioUrl
             )
 
             // Parse tags from JSON stored in LocalPost