fix: apply default room preference on app load

- Root `/` now redirects to user's preferred default room
- Front Hall moved to `/front-hall` route (was `/`)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

lib/routing/app_router.dart

@@ -1,6 +1,7 @@
 import 'package:flutter/material.dart';
 import 'package:go_router/go_router.dart';
 import 'package:riverpod_annotation/riverpod_annotation.dart';
+import 'package:tatlock_ui/core/auth/auth_provider.dart';
 import 'package:tatlock_ui/features/control_room/router.dart';
 import 'package:tatlock_ui/features/front_hall/presentation/pages/front_hall_page.dart';
 import 'package:tatlock_ui/features/security/router.dart';
@@ -19,18 +20,44 @@ Page<void> noTransitionPage(BuildContext context, GoRouterState state, Widget ch
 
 /// Route paths as constants.
 abstract class AppRoutes {
-  static const frontHall = '/';
+  static const root = '/';
+  static const frontHall = '/front-hall';
   static const parlor = '/parlor';
   static const settings = '/settings';
 }
 
+/// Maps defaultRoom preference value to route path.
+String _routeForDefaultRoom(String? defaultRoom) {
+  return switch (defaultRoom) {
+    'control-room' => ControlRoomRoutes.containers,
+    'security' => SecurityRoutes.users,
+    'parlor' => AppRoutes.parlor,
+    _ => AppRoutes.frontHall,
+  };
+}
+
 /// Provides the GoRouter instance.
 @riverpod
 GoRouter appRouter(Ref ref) {
+  final authState = ref.watch(authProvider);
+
   return GoRouter(
-    initialLocation: AppRoutes.frontHall,
+    initialLocation: AppRoutes.root,
     debugLogDiagnostics: true,
+    redirect: (context, state) {
+      // Redirect from root to user's default room preference
+      if (state.matchedLocation == AppRoutes.root) {
+        final defaultRoom = authState.value?.preferences?.defaultRoom;
+        return _routeForDefaultRoom(defaultRoom);
+      }
+      return null;
+    },
     routes: [
+      // Root redirects to default room (handled by redirect callback above)
+      GoRoute(
+        path: AppRoutes.root,
+        redirect: (context, state) => AppRoutes.frontHall,
+      ),
       // Main app routes (inside shell with app scaffold)
       ShellRoute(
         builder: (context, state, child) => AppScaffold(child: child),