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/domain/incoming_call.dart

@@ -0,0 +1,18 @@
+// Version: 1.1.0 | Created: 2026-04-01
+// IncomingCall — immutable model representing a received m.call.invite.
+
+import 'package:freezed_annotation/freezed_annotation.dart';
+
+part 'incoming_call.freezed.dart';
+
+@freezed
+abstract class IncomingCall with _$IncomingCall {
+  const factory IncomingCall({
+    required String callId,
+    required String roomId,
+    required String callerId,
+    required String callerDisplayName,
+    String? callerAvatarUrl,
+    @Default(false) bool isVideo,
+  }) = _IncomingCall;
+}