Phase 3.1: Complete mitra_app Riverpod migration (all blocs, fix auth bug)

- Migrate AuthBloc → MitraAuthNotifier (fixes stuck-loading bug: now returns
  MitraAuthInitialData when currentUser is null)
- Migrate StatusBloc → OnlineStatusNotifier (heartbeat timer + lifecycle)
- Migrate ExtensionBloc → MitraExtensionNotifier (accept/reject + goodbye)
- Migrate ChatRequestBloc → ChatRequestNotifier (WebSocket incoming requests)
- Migrate MitraChatBloc → MitraChatNotifier (WebSocket chat + messages)
- Update router to use Riverpod auth state for redirects
- Remove all flutter_bloc usage from mitra_app screens and main.dart
- MultiBlocProvider fully removed from mitra_app

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mitra_app/lib/core/status/status_notifier.dart

@@ -0,0 +1,97 @@
+import 'dart:async';
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import '../api/api_client_provider.dart';
+
+part 'status_notifier.g.dart';
+
+// States
+sealed class OnlineStatusData {
+  const OnlineStatusData();
+}
+
+class StatusInitialData extends OnlineStatusData {
+  const StatusInitialData();
+}
+
+class StatusLoadedData extends OnlineStatusData {
+  final bool isOnline;
+  const StatusLoadedData({required this.isOnline});
+}
+
+class StatusLoadingData extends OnlineStatusData {
+  const StatusLoadingData();
+}
+
+class StatusErrorData extends OnlineStatusData {
+  final String message;
+  const StatusErrorData(this.message);
+}
+
+@Riverpod(keepAlive: true)
+class OnlineStatus extends _$OnlineStatus {
+  Timer? _heartbeatTimer;
+
+  @override
+  OnlineStatusData build() => const StatusInitialData();
+
+  Future<void> load() async {
+    try {
+      final response = await ref.read(apiClientProvider).get('/api/mitra/status');
+      final data = response['data'] as Map<String, dynamic>;
+      state = StatusLoadedData(isOnline: data['is_online'] as bool);
+    } catch (e) {
+      state = const StatusLoadedData(isOnline: false);
+    }
+  }
+
+  Future<void> toggleOnline() async {
+    state = const StatusLoadingData();
+    try {
+      await ref.read(apiClientProvider).post('/api/mitra/status/online');
+      _startHeartbeat();
+      state = const StatusLoadedData(isOnline: true);
+    } catch (e) {
+      state = const StatusErrorData('Gagal mengubah status. Coba lagi.');
+    }
+  }
+
+  Future<void> toggleOffline() async {
+    state = const StatusLoadingData();
+    try {
+      await ref.read(apiClientProvider).post('/api/mitra/status/offline');
+      _stopHeartbeat();
+      state = const StatusLoadedData(isOnline: false);
+    } catch (e) {
+      state = const StatusErrorData('Gagal mengubah status. Coba lagi.');
+    }
+  }
+
+  void onAppPaused() {
+    _stopHeartbeat();
+  }
+
+  void onAppResumed() {
+    if (state is StatusLoadedData && (state as StatusLoadedData).isOnline) {
+      _startHeartbeat();
+    }
+    load();
+  }
+
+  void _startHeartbeat() {
+    _stopHeartbeat();
+    _heartbeatTimer = Timer.periodic(const Duration(seconds: 15), (_) {
+      _heartbeatTick();
+    });
+  }
+
+  void _stopHeartbeat() {
+    _heartbeatTimer?.cancel();
+    _heartbeatTimer = null;
+  }
+
+  Future<void> _heartbeatTick() async {
+    try {
+      await ref.read(apiClientProvider).post('/api/mitra/status/heartbeat');
+    } catch (_) {}
+  }
+}

mitra_app/lib/core/status/status_notifier.g.dart

@@ -0,0 +1,25 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'status_notifier.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+String _$onlineStatusHash() => r'6b42328eaba0f7934b0e3eaa54eb6b764f1c4e53';
+
+/// See also [OnlineStatus].
+@ProviderFor(OnlineStatus)
+final onlineStatusProvider =
+    NotifierProvider<OnlineStatus, OnlineStatusData>.internal(
+  OnlineStatus.new,
+  name: r'onlineStatusProvider',
+  debugGetCreateSourceHash:
+      const bool.fromEnvironment('dart.vm.product') ? null : _$onlineStatusHash,
+  dependencies: null,
+  allTransitiveDependencies: null,
+);
+
+typedef _$OnlineStatus = Notifier<OnlineStatusData>;
+// ignore_for_file: type=lint
+// ignore_for_file: subtype_of_sealed_class, invalid_use_of_internal_member, invalid_use_of_visible_for_testing_member, deprecated_member_use_from_same_package