Phase 3.2 WS1: Chat request overlay, queue, stale reasons

- Backend: add reason field to chat_request_closed WS messages
  (cancelled_by_customer, accepted_by_other, expired)
- Backend: include duration_minutes, is_free_trial in chat_request WS
- ChatRequestNotifier: add ChatRequestStaleData, StaleReason enum,
  request queue (List<Map>), ignore(), acknowledgeStale(), _advanceQueue()
- New ChatRequestOverlay widget: slides up from bottom, dimmed background,
  swipe to dismiss, shows active/stale request content
- Integrate overlay in main.dart wrapping MaterialApp.router
- Cleanup: convert HomeScreen to ConsumerWidget, remove showModalBottomSheet,
  remove IncomingRequestSheet, remove lifecycle observer

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

mitra_app/lib/features/home/home_screen.dart

@@ -5,54 +5,12 @@ import '../../core/auth/auth_notifier.dart';
 import '../../core/status/status_notifier.dart';
 import '../../core/chat/chat_request_notifier.dart';
 import '../../core/chat/unread_notifier.dart';
-import '../chat/widgets/incoming_request_sheet.dart';
 
-class HomeScreen extends ConsumerStatefulWidget {
+class HomeScreen extends ConsumerWidget {
   const HomeScreen({super.key});
 
   @override
-  ConsumerState<HomeScreen> createState() => _HomeScreenState();
-}
-
-class _HomeScreenState extends ConsumerState<HomeScreen> with WidgetsBindingObserver {
-  @override
-  void initState() {
-    super.initState();
-    WidgetsBinding.instance.addObserver(this);
-  }
-
-  @override
-  void dispose() {
-    WidgetsBinding.instance.removeObserver(this);
-    super.dispose();
-  }
-
-  @override
-  void didChangeAppLifecycleState(AppLifecycleState state) {
-    if (state == AppLifecycleState.resumed) {
-      final chatState = ref.read(chatRequestProvider);
-      if (chatState is ChatRequestIncomingData) {
-        // Validate the request is still pending before showing
-        ref.read(chatRequestProvider.notifier).validateIncomingRequest().then((_) {
-          final current = ref.read(chatRequestProvider);
-          if (current is ChatRequestIncomingData) {
-            _showIncomingRequest(current.sessionId);
-          }
-        });
-      }
-    }
-  }
-
-  void _showIncomingRequest(String sessionId) {
-    showModalBottomSheet(
-      context: context,
-      isDismissible: false,
-      builder: (_) => IncomingRequestSheet(sessionId: sessionId),
-    );
-  }
-
-  @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
     final authState = ref.watch(mitraAuthProvider);
     final authData = authState.valueOrNull;
     final displayName = authData is MitraAuthAuthenticatedData
@@ -68,19 +26,6 @@ class _HomeScreenState extends ConsumerState<HomeScreen> with WidgetsBindingObse
       }
     });
 
-    // Listen for incoming chat requests — fresh from WS, show immediately
-    ref.listen(chatRequestProvider, (prev, next) {
-      if (next is ChatRequestIncomingData) {
-        _showIncomingRequest(next.sessionId);
-      } else if (next is ChatRequestAcceptedData) {
-        final session = next.session;
-        final sessionId = session['session_id'] as String? ?? session['id'] as String;
-        context.push('/chat/session/$sessionId', extra: {
-          'customerName': session['customer_display_name'] as String? ?? 'Customer',
-        });
-      }
-    });
-
     return Scaffold(
       appBar: AppBar(
         title: const Text('Halo Bestie Mitra'),