feat: User/onboarding persistence — save to DB, load on startup [AITM-233]

lib/core/router/app_router.dart

@@ -1,6 +1,8 @@
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
 
+import '../../features/onboarding/screens/onboarding_screen.dart';
+import '../../features/tasks/providers/task_providers.dart';
 import '../../features/tasks/screens/tasks_screen.dart';
 import '../../features/tasks/screens/pet_screen.dart';
 import '../../features/zen_mode/screens/zen_screen.dart';
@@ -9,9 +11,28 @@ import '../../shared/widgets/app_shell.dart';
 import 'routes.dart';
 
 final appRouterProvider = Provider<GoRouter>((ref) {
+  final currentUser = ref.watch(currentUserProvider);
+
   return GoRouter(
     initialLocation: Routes.tasks,
+    redirect: (context, state) {
+      final isOnboarding = state.matchedLocation == Routes.onboarding;
+
+      // While loading user from DB, don't redirect
+      if (currentUser.isLoading) return null;
+
+      final hasUser = currentUser.value != null;
+
+      if (!hasUser && !isOnboarding) return Routes.onboarding;
+      if (hasUser && isOnboarding) return Routes.tasks;
+      return null;
+    },
     routes: [
+      // Onboarding — outside shell, no bottom nav
+      GoRoute(
+        path: Routes.onboarding,
+        builder: (context, state) => const OnboardingScreen(),
+      ),
       StatefulShellRoute.indexedStack(
         builder: (context, state, navigationShell) {
           return AppShell(navigationShell: navigationShell);

lib/features/onboarding/screens/onboarding_screen.dart

@@ -1,11 +1,14 @@
+import 'dart:io';
+
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:go_router/go_router.dart';
-import 'package:shared_preferences/shared_preferences.dart';
+import 'package:uuid/uuid.dart';
 
 import '../../../core/theme/kittie_colors.dart';
 import '../../../core/theme/kittie_typography.dart';
 import '../../../domain/entities/pet_type.dart';
+import '../../tasks/providers/task_providers.dart';
 import '../providers/onboarding_providers.dart';
 
 class OnboardingScreen extends ConsumerStatefulWidget {
@@ -43,13 +46,23 @@ class _OnboardingScreenState extends ConsumerState<OnboardingScreen> {
   }
 
   Future<void> _completeOnboarding() async {
-    final prefs = await SharedPreferences.getInstance();
-    await prefs.setBool('onboarding_complete', true);
-    await prefs.setString(
-      'pet_type',
-      ref.read(selectedPetTypeProvider).name,
+    final repo = ref.read(userRepositoryProvider);
+    final petType = ref.read(selectedPetTypeProvider);
+    final petName = ref.read(petNameProvider);
+
+    const uuid = Uuid();
+    final userId = uuid.v4();
+    final deviceId = '${Platform.operatingSystem}-${uuid.v4()}';
+
+    await repo.createUser(
+      id: userId,
+      deviceId: deviceId,
+      name: 'Friend',
+      petType: petType,
+      petName: petName,
     );
-    await prefs.setString('pet_name', ref.read(petNameProvider));
+
+    ref.invalidate(currentUserProvider);
 
     if (mounted) {
       context.go('/tasks');

lib/features/tasks/providers/pet_providers.dart

@@ -22,18 +22,34 @@ enum PetMood {
 
 class UserNotifier extends Notifier<UserEntity> {
   @override
-  UserEntity build() => UserEntity(
-        id: '1',
+  UserEntity build() {
+    final currentUser = ref.watch(currentUserProvider).value;
+    if (currentUser != null) return currentUser;
+    return UserEntity(
+      id: '',
       name: 'Friend',
       petType: PetType.cat,
       petName: 'Yoshi',
       createdAt: DateTime.now(),
       updatedAt: DateTime.now(),
     );
+  }
 
-  void updateName(String name) => state = state.copyWith(name: name);
-  void updatePetName(String petName) =>
-      state = state.copyWith(petName: petName);
+  void updateName(String name) {
+    state = state.copyWith(name: name, updatedAt: DateTime.now());
+    _persist();
+  }
+
+  void updatePetName(String petName) {
+    state = state.copyWith(petName: petName, updatedAt: DateTime.now());
+    _persist();
+  }
+
+  void _persist() {
+    if (state.id.isEmpty) return;
+    final repo = ref.read(userRepositoryProvider);
+    repo.updateUser(state);
+  }
 }
 
 final userProvider =

lib/features/tasks/providers/task_providers.dart

@@ -34,12 +34,12 @@ final currentUserProvider = FutureProvider<UserEntity?>((ref) {
 
 // ── Task list (reactive stream from DB) ──
 
-const _userId = 'user-1';
-
 /// All tasks for the current user, streamed from Drift.
 final tasksProvider = StreamProvider<List<TaskEntity>>((ref) {
+  final user = ref.watch(currentUserProvider).value;
+  if (user == null) return Stream.value([]);
   final repo = ref.watch(taskRepositoryProvider);
-  return repo.watchTasks(_userId);
+  return repo.watchTasks(user.id);
 });
 
 /// Alias for [tasksProvider]. Returns all tasks — no date filtering in MVP.

lib/features/tasks/screens/add_task_screen.dart

@@ -7,6 +7,7 @@ import '../../../core/theme/kittie_colors.dart';
 import '../../../core/theme/kittie_typography.dart';
 import '../../../domain/entities/task_entity.dart';
 import '../providers/add_task_providers.dart';
+import '../providers/pet_providers.dart';
 import '../providers/task_providers.dart';
 
 /// Shows the Add Task bottom sheet. Call from any screen:
@@ -59,7 +60,7 @@ class _AddTaskSheetState extends ConsumerState<_AddTaskSheet> {
 
     final entity = TaskEntity(
       id: const Uuid().v4(),
-      userId: 'user-1',
+      userId: ref.read(userProvider).id,
       title: title,
       description: note.isEmpty ? null : note,
       energyLevel: energy,