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/auth/auth_notifier.dart

@@ -0,0 +1,114 @@
+import 'dart:async';
+import 'package:firebase_auth/firebase_auth.dart';
+import 'package:flutter/foundation.dart' show kIsWeb;
+import 'package:riverpod_annotation/riverpod_annotation.dart';
+import '../api/api_client.dart';
+import '../api/api_client_provider.dart';
+
+part 'auth_notifier.g.dart';
+
+// States
+sealed class MitraAuthData {
+  const MitraAuthData();
+}
+
+class MitraAuthInitialData extends MitraAuthData {
+  const MitraAuthInitialData();
+}
+
+class MitraAuthAuthenticatedData extends MitraAuthData {
+  final Map<String, dynamic> profile;
+  const MitraAuthAuthenticatedData(this.profile);
+}
+
+class MitraAuthOtpSentData extends MitraAuthData {
+  final String verificationId;
+  const MitraAuthOtpSentData(this.verificationId);
+}
+
+@Riverpod(keepAlive: true)
+class MitraAuth extends _$MitraAuth {
+  FirebaseAuth get _auth => FirebaseAuth.instance;
+  ApiClient get _apiClient => ref.read(apiClientProvider);
+  ConfirmationResult? _webConfirmationResult;
+
+  @override
+  FutureOr<MitraAuthData> build() async {
+    if (_auth.currentUser != null) {
+      return await _verifyAndReturn();
+    }
+    return const MitraAuthInitialData(); // FIX: was missing in BLoC version
+  }
+
+  Future<void> requestOtp(String phone) async {
+    state = const AsyncLoading();
+    if (kIsWeb) {
+      try {
+        final confirmationResult = await _auth.signInWithPhoneNumber(phone);
+        _webConfirmationResult = confirmationResult;
+        state = const AsyncData(MitraAuthOtpSentData('web'));
+      } catch (e) {
+        state = AsyncError('Gagal mengirim OTP. Coba lagi.', StackTrace.current);
+      }
+    } else {
+      final completer = Completer<void>();
+      await _auth.verifyPhoneNumber(
+        phoneNumber: phone,
+        verificationCompleted: (_) {
+          if (!completer.isCompleted) completer.complete();
+        },
+        verificationFailed: (e) {
+          state = AsyncError('Gagal mengirim OTP. Coba lagi.', StackTrace.current);
+          if (!completer.isCompleted) completer.complete();
+        },
+        codeSent: (verificationId, _) {
+          state = AsyncData(MitraAuthOtpSentData(verificationId));
+          if (!completer.isCompleted) completer.complete();
+        },
+        codeAutoRetrievalTimeout: (_) {
+          if (!completer.isCompleted) completer.complete();
+        },
+      );
+      await completer.future;
+    }
+  }
+
+  Future<void> verifyOtp(String verificationId, String smsCode) async {
+    state = const AsyncLoading();
+    try {
+      if (kIsWeb && _webConfirmationResult != null) {
+        await _webConfirmationResult!.confirm(smsCode);
+      } else {
+        final credential = PhoneAuthProvider.credential(
+          verificationId: verificationId,
+          smsCode: smsCode,
+        );
+        await _auth.signInWithCredential(credential);
+      }
+      state = AsyncData(await _verifyAndReturn());
+    } catch (e) {
+      state = AsyncError('OTP tidak valid. Coba lagi.', StackTrace.current);
+    }
+  }
+
+  Future<void> logout() async {
+    await _auth.signOut();
+    state = const AsyncData(MitraAuthInitialData());
+  }
+
+  Future<MitraAuthData> _verifyAndReturn() async {
+    try {
+      final response = await _apiClient.post('/api/mitra/auth/verify');
+      return MitraAuthAuthenticatedData(response['data'] as Map<String, dynamic>);
+    } on Exception catch (e) {
+      await _auth.signOut();
+      final msg = e.toString();
+      if (msg.contains('ACCOUNT_NOT_FOUND')) {
+        throw Exception('Akun tidak ditemukan. Hubungi administrator.');
+      } else if (msg.contains('ACCOUNT_INACTIVE')) {
+        throw Exception('Akun tidak aktif. Hubungi administrator.');
+      }
+      throw Exception('Gagal masuk. Coba lagi.');
+    }
+  }
+}

mitra_app/lib/core/auth/auth_notifier.g.dart

@@ -0,0 +1,25 @@
+// GENERATED CODE - DO NOT MODIFY BY HAND
+
+part of 'auth_notifier.dart';
+
+// **************************************************************************
+// RiverpodGenerator
+// **************************************************************************
+
+String _$mitraAuthHash() => r'65235a41cde3a37feef0b3004a0a48b508bf9ac9';
+
+/// See also [MitraAuth].
+@ProviderFor(MitraAuth)
+final mitraAuthProvider =
+    AsyncNotifierProvider<MitraAuth, MitraAuthData>.internal(
+  MitraAuth.new,
+  name: r'mitraAuthProvider',
+  debugGetCreateSourceHash:
+      const bool.fromEnvironment('dart.vm.product') ? null : _$mitraAuthHash,
+  dependencies: null,
+  allTransitiveDependencies: null,
+);
+
+typedef _$MitraAuth = AsyncNotifier<MitraAuthData>;
+// 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