feat: Phase 2 complete — calls, media, spaces, persistence, chat improvements

- LiveKit/MatrixRTC voice+video calls with full call screen UI
- Incoming call overlay (accept/decline)
- Media upload/download — file picker, image rendering, file download
- Spaces navigation — space list + expandable child rooms
- Drift persistence — rooms + messages written on every sync
- Sync persistence auto-starts on login and session restore
- Chat: typing indicators, long-press menu, reply, emoji reactions
- User search dialog + start DM from rooms screen
- Android: INTERNET + CAMERA + RECORD_AUDIO permissions in main manifest
- Emoji picker for reactions

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/features/calls/data/matrixrtc_repository.dart

@@ -0,0 +1,119 @@
+// Version: 1.1.0 | Created: 2026-04-01
+// MatrixRTC repository — handles outgoing call invites and detects incoming
+// calls via m.call.invite events per MSC4143 (MatrixRTC spec).
+//
+// Incoming calls are surfaced via the incomingCallStream so the
+// IncomingCallOverlay can react to them.
+
+import 'dart:async';
+
+import 'package:matrix/matrix.dart';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+
+import '../../../core/auth/auth_notifier.dart';
+import '../../../core/auth/auth_state.dart';
+import '../../../core/network/matrix_client.dart';
+import '../domain/incoming_call.dart';
+
+part 'matrixrtc_repository.g.dart';
+
+/// Repository for sending and receiving MatrixRTC call signalling events.
+class MatrixRtcRepository {
+  MatrixRtcRepository({required Client client, required String? myUserId})
+    : _client = client,
+      _myUserId = myUserId;
+
+  final Client _client;
+  final String? _myUserId;
+
+  final _incomingCallController = StreamController<IncomingCall>.broadcast();
+
+  /// Emits whenever an incoming call invite arrives for the local user.
+  Stream<IncomingCall> get incomingCallStream => _incomingCallController.stream;
+
+  StreamSubscription<EventUpdate>? _eventSubscription;
+
+  /// Begin listening for incoming m.call.invite events.
+  void startListening() {
+    _eventSubscription?.cancel();
+    _eventSubscription = _client.onEvent.stream.listen(_onEvent);
+  }
+
+  void stopListening() {
+    _eventSubscription?.cancel();
+    _eventSubscription = null;
+    _incomingCallController.close();
+  }
+
+  /// Send a call invite to [roomId] to start a voice or video call.
+  ///
+  /// Uses the standard m.call.invite event type. The room's other participants
+  /// will receive this via their sync stream.
+  Future<void> sendCallInvite({
+    required String roomId,
+    required bool isVideo,
+  }) async {
+    final room = _client.getRoomById(roomId);
+    if (room == null) return;
+
+    final callId = 'call_${DateTime.now().millisecondsSinceEpoch}';
+
+    await room.sendEvent({
+      'msgtype': 'm.call.invite',
+      'call_id': callId,
+      'lifetime': 60000, // 60 seconds before invite expires
+      'offer': {
+        'type': 'offer',
+        'sdp': '', // SDP is populated by LiveKit once connected
+      },
+      'version': '1',
+      'invitee': null, // null = invite entire room
+      'm.intentional_mentions': {'user_ids': [], 'room': false},
+    }, type: 'm.call.invite');
+  }
+
+  void _onEvent(EventUpdate update) {
+    if (update.type != EventUpdateType.timeline) return;
+    if (update.content['type'] != 'm.call.invite') return;
+
+    final senderId = update.content['sender'] as String?;
+    // Ignore our own invites.
+    if (senderId == _myUserId) return;
+
+    final roomId = update.roomID;
+    final content = update.content['content'] as Map<String, dynamic>?;
+    if (content == null) return;
+
+    final callId = content['call_id'] as String?;
+    if (callId == null) return;
+
+    final room = _client.getRoomById(roomId);
+    final senderProfile = room?.unsafeGetUserFromMemoryOrFallback(
+      senderId ?? '',
+    );
+
+    _incomingCallController.add(
+      IncomingCall(
+        callId: callId,
+        roomId: roomId,
+        callerId: senderId ?? '',
+        callerDisplayName:
+            senderProfile?.displayName ?? senderId?.split(':').first ?? '',
+        callerAvatarUrl: senderProfile?.avatarUrl?.toString(),
+        isVideo: (content['offer'] != null),
+      ),
+    );
+  }
+}
+
+@Riverpod(keepAlive: true)
+MatrixRtcRepository matrixRtcRepository(Ref ref) {
+  final client = ref.watch(matrixClientProvider);
+  final authState = ref.watch(authProvider);
+  final myUserId = authState is AuthAuthenticated ? authState.userId : null;
+
+  final repo = MatrixRtcRepository(client: client, myUserId: myUserId);
+  repo.startListening();
+  ref.onDispose(repo.stopListening);
+  return repo;
+}