feat: show "Publishing to" chip in Composer for multi-account users

When more than one account is configured, display an informational
AssistChip at the top of the Composer showing the active blog name
and site icon. Uses SiteMetadataCache for the blog title, falls back
to account name. Non-clickable, only shown for disambiguation.

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

@@ -42,8 +42,12 @@ import androidx.compose.ui.window.Dialog
 import androidx.compose.ui.window.DialogProperties
 import androidx.lifecycle.compose.collectAsStateWithLifecycle
 import androidx.lifecycle.viewmodel.compose.viewModel
+import androidx.compose.foundation.shape.CircleShape
+import androidx.compose.ui.platform.LocalContext
 import coil.compose.AsyncImage
+import com.swoosh.microblog.data.AccountManager
 import com.swoosh.microblog.data.HashtagParser
+import com.swoosh.microblog.data.SiteMetadataCache
 import com.swoosh.microblog.data.model.FeedPost
 import com.swoosh.microblog.data.model.PostStats
 import com.swoosh.microblog.ui.animation.SwooshMotion
@@ -209,6 +213,39 @@ fun ComposerScreen(
                 .fillMaxSize()
                 .padding(padding)
         ) {
+            // "Publishing to" chip when multiple accounts exist
+            val composerContext = LocalContext.current
+            val composerAccountManager = remember { AccountManager(composerContext) }
+            val composerAccounts = remember { composerAccountManager.getAccounts() }
+            val composerActiveAccount = remember { composerAccountManager.getActiveAccount() }
+
+            if (composerAccounts.size > 1 && composerActiveAccount != null) {
+                val composerSiteCache = remember { SiteMetadataCache(composerContext) }
+                val composerSiteData = remember {
+                    composerSiteCache.get(composerActiveAccount.id)
+                }
+                val siteName = composerSiteData?.title ?: composerActiveAccount.name
+                val siteIconUrl = composerSiteData?.icon ?: composerSiteData?.logo
+
+                AssistChip(
+                    onClick = { },
+                    label = { Text("Publishing to: $siteName") },
+                    leadingIcon = if (siteIconUrl != null) {
+                        {
+                            AsyncImage(
+                                model = siteIconUrl,
+                                contentDescription = null,
+                                modifier = Modifier
+                                    .size(18.dp)
+                                    .clip(CircleShape),
+                                contentScale = ContentScale.Crop
+                            )
+                        }
+                    } else null,
+                    modifier = Modifier.padding(horizontal = 16.dp, vertical = 4.dp)
+                )
+            }
+
             // Hashtag visual transformation for edit mode text field
             val hashtagColor = MaterialTheme.colorScheme.primary
             val hashtagTransformation = remember(hashtagColor) {