Fix device sync: folder status badges, remove-deletes-local, multi-select, header summary

- Folders now show the synced status badge themselves, not just their
  nested files - device-sync state never tracked folders individually, so
  syncStatusFor derives a folder's badge from whether its path falls
  within sync scope instead.
- Turning sync off for a path now deletes its local mirror and clears its
  native sync-state entries (SyncEngine.removeLocalSync), instead of just
  stopping future updates and leaving the downloaded copy behind.
- "Sync to device" in Files' selection toolbar now works over the whole
  selection at once instead of being gated to a single selected item.
- The sync header's expanded panel shows real folder/item counts instead
  of a static "Synced" label that stayed accurate-sounding even before
  anything had actually synced.
- Confirmation SnackBars on starting/stopping sync from both the
  selection toolbar and Settings' Device Sync card.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

android/app/src/main/kotlin/dev/ayushya/noo/MainActivity.kt

@@ -136,6 +136,7 @@ class MainActivity : FlutterFragmentActivity() {
                     "syncNow" -> syncNow(call, result)
                     "getSyncStatus" -> result.success(syncStatusMap(SyncStatusBus.snapshot()))
                     "resolveConflict" -> resolveConflict(call, result)
+                    "removeLocalSync" -> removeLocalSync(call, result)
                     else -> result.notImplemented()
                 }
             }
@@ -405,6 +406,24 @@ class MainActivity : FlutterFragmentActivity() {
         result.success(null)
     }
 
+    /// Deletes a path's local mirror once the user turns sync off for it -
+    /// see [SyncEngine.removeLocalSync]. Runs off the main thread since it
+    /// walks/deletes a directory tree; `result.success` is posted back via
+    /// [mainHandler] since MethodChannel results must be delivered on the
+    /// platform thread.
+    private fun removeLocalSync(call: MethodCall, result: MethodChannel.Result) {
+        val accountId = call.argument<String>("accountId")
+        val path = call.argument<String>("path")
+        if (accountId == null || path == null) {
+            result.error("bad_args", "Missing required arguments", null)
+            return
+        }
+        Thread {
+            SyncEngine.removeLocalSync(applicationContext, accountId, path)
+            mainHandler.post { result.success(null) }
+        }.start()
+    }
+
     /// One-off immediate run (Settings' "Sync now"), independent of the
     /// periodic schedule.
     private fun syncNow(call: MethodCall, result: MethodChannel.Result) {

android/app/src/main/kotlin/dev/ayushya/noo/SyncEngine.kt

@@ -356,6 +356,35 @@ object SyncEngine {
         return actions
     }
 
+    /**
+     * Deletes [path]'s local mirror (a single file, or a whole folder's
+     * worth of files) and removes its entries from the persisted sync-state
+     * map, called when the user turns sync off for that path - without
+     * clearing the state too, a later re-add would see the (now missing)
+     * local file as "deleted, server unchanged" and skip re-downloading it
+     * (see [diffFolder]'s `!localExists && !serverChanged` branch) instead
+     * of pulling it back down.
+     */
+    fun removeLocalSync(context: Context, accountId: String, path: String) {
+        val root = syncRoot(context, accountId)
+        val state = loadState(context, accountId).toMutableMap()
+
+        var cleanPath = path.trim()
+        if (cleanPath.startsWith("/")) cleanPath = cleanPath.substring(1)
+        cleanPath = cleanPath.trimEnd('/')
+        val prefix = if (cleanPath.isEmpty()) "" else "$cleanPath/"
+
+        val toRemove = state.filterValues { s ->
+            s.relPath == cleanPath || (prefix.isNotEmpty() && s.relPath.startsWith(prefix))
+        }.keys
+        for (fileId in toRemove) state.remove(fileId)
+        saveState(context, accountId, state)
+
+        val target = if (cleanPath.isEmpty()) root else File(root, cleanPath)
+        if (target.exists()) target.deleteRecursively()
+        Log.d(TAG, "removeLocalSync($path) -> removed ${toRemove.size} state entries")
+    }
+
     fun folderIsSyncedUnder(itemPath: String, syncedFolders: List<String>): String? {
         val normalizedItem = itemPath.trimEnd('/')
         for (folder in syncedFolders) {