Phase 3.1: Remove flutter_bloc + equatable, delete old bloc files

- Remove flutter_bloc and equatable dependencies from both apps
- Delete all 10 old bloc files (5 per app)
- Fix 6 remaining screens that used context.read<ApiClient>() from
  flutter_bloc → converted to ConsumerStatefulWidget/ConsumerWidget
  with ref.read(apiClientProvider)
- Both apps now use Riverpod exclusively for state management

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

client_app/lib/features/chat/screens/session_active_screen.dart

@@ -1,9 +1,9 @@
 import 'package:flutter/material.dart';
-import 'package:flutter_bloc/flutter_bloc.dart';
+import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
-import '../../../core/api/api_client.dart';
+import '../../../core/api/api_client_provider.dart';
 
-class SessionActiveScreen extends StatelessWidget {
+class SessionActiveScreen extends ConsumerWidget {
   final String sessionId;
   final String mitraName;
 
@@ -14,7 +14,7 @@ class SessionActiveScreen extends StatelessWidget {
   });
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
     return Scaffold(
       appBar: AppBar(
         title: const Text('Sesi Aktif'),
@@ -42,7 +42,7 @@ class SessionActiveScreen extends StatelessWidget {
               const SizedBox(height: 48),
               ElevatedButton(
                 style: ElevatedButton.styleFrom(backgroundColor: Colors.red),
-                onPressed: () => _endSession(context),
+                onPressed: () => _endSession(context, ref),
                 child: const Text('Akhiri Sesi', style: TextStyle(color: Colors.white)),
               ),
             ],
@@ -52,7 +52,7 @@ class SessionActiveScreen extends StatelessWidget {
     );
   }
 
-  Future<void> _endSession(BuildContext context) async {
+  Future<void> _endSession(BuildContext context, WidgetRef ref) async {
     final confirmed = await showDialog<bool>(
       context: context,
       builder: (ctx) => AlertDialog(
@@ -67,7 +67,7 @@ class SessionActiveScreen extends StatelessWidget {
 
     if (confirmed == true && context.mounted) {
       try {
-        final apiClient = context.read<ApiClient>();
+        final apiClient = ref.read(apiClientProvider);
         await apiClient.post('/api/client/chat/session/$sessionId/end');
         if (context.mounted) context.go('/home');
       } catch (_) {