Add visual save indicator button for rooms

- Add bookmark icon button in room header to toggle save status
- Use bookmark.fill when room is saved, bookmark when not
- Button shows yellow when saved, default color when not
- Integrate with existing /save command functionality
- Add savedRooms published property for reactive UI updates

bitchat/ViewModels/ChatViewModel.swift

@@ -48,6 +48,7 @@ class ChatViewModel: ObservableObject {
     @Published var roomKeyCommitments: [String: String] = [:]  // room -> SHA256(derivedKey) for verification
     @Published var showPasswordPrompt: Bool = false
     @Published var passwordPromptRoom: String? = nil
+    @Published var savedRooms: Set<String> = []  // Rooms saved for message retention
     
     let meshService = BluetoothMeshService()
     private let userDefaults = UserDefaults.standard
@@ -70,6 +71,7 @@ class ChatViewModel: ObservableObject {
         loadFavorites()
         loadJoinedRooms()
         loadRoomData()
+        savedRooms = MessageRetentionService.shared.getFavoriteRooms()
         meshService.delegate = self
         
         // Log startup info
@@ -930,6 +932,7 @@ class ChatViewModel: ObservableObject {
         
         // Clear all retained messages
         MessageRetentionService.shared.deleteAllStoredMessages()
+        savedRooms.removeAll()
         
         // Clear message retry queue
         MessageRetryService.shared.clearRetryQueue()
@@ -1590,6 +1593,13 @@ extension ChatViewModel: BitchatDelegate {
             let isFavorite = MessageRetentionService.shared.toggleFavoriteRoom(room)
             let status = isFavorite ? "saved" : "unsaved"
             
+            // Update published property
+            if isFavorite {
+                savedRooms.insert(room)
+            } else {
+                savedRooms.remove(room)
+            }
+            
             // If just marked as favorite, load any previously saved messages
             if isFavorite {
                 let savedMessages = MessageRetentionService.shared.loadMessagesForRoom(room)

bitchat/Views/ContentView.swift

@@ -296,6 +296,16 @@ struct ContentView: View {
                 Spacer()
                 
                 HStack(spacing: 8) {
+                    // Save button
+                    Button(action: {
+                        viewModel.sendMessage("/save")
+                    }) {
+                        Image(systemName: viewModel.savedRooms.contains(currentRoom) ? "bookmark.fill" : "bookmark")
+                            .font(.system(size: 16))
+                            .foregroundColor(viewModel.savedRooms.contains(currentRoom) ? Color.yellow : textColor)
+                    }
+                    .buttonStyle(.plain)
+                    
                     // Password button for room creator only
                     if viewModel.roomCreators[currentRoom] == viewModel.meshService.myPeerID {
                         Button(action: {