feat: add local-first private AI digest workflow

Migrate app code into canonical feature slices, add phone-only AI digest scheduling and review, wire local notification/background task support, and cover the flow with tests.

lib/main.dart

@@ -1,44 +1,60 @@
+import 'dart:async';
+
+import 'package:flutter/foundation.dart';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
-import 'package:relationship_saver/core/config/app_theme.dart';
-import 'package:relationship_saver/features/auth/session_controller.dart';
-import 'package:relationship_saver/features/auth/sign_in_view.dart';
-import 'package:relationship_saver/features/home/app_shell.dart';
-import 'package:relationship_saver/features/reminders/scheduling/reminder_notification_listener.dart';
-import 'package:relationship_saver/features/share_intake/whatsapp_share_listener.dart';
-import 'package:relationship_saver/features/sync/sync_background_runner.dart';
-import 'package:relationship_saver/integrations/backend/models/backend_models.dart';
+import 'package:relationship_saver/app/relationship_saver_app.dart';
+import 'package:relationship_saver/core/observability/sentry_init.dart';
+import 'package:relationship_saver/features/ai_digest/application/llm_digest_background_scheduler.dart';
+import 'package:relationship_saver/features/ai_digest/application/llm_digest_orchestrator.dart';
+import 'package:workmanager/workmanager.dart';
 
-void main() {
-  runApp(const ProviderScope(child: RelationshipSaverApp()));
+export 'package:relationship_saver/app/relationship_saver_app.dart';
+
+@pragma('vm:entry-point')
+void llmDigestCallbackDispatcher() {
+  Workmanager().executeTask((
+    String taskName,
+    Map<String, dynamic>? inputData,
+  ) async {
+    if (taskName != llmDigestTaskName &&
+        taskName != Workmanager.iOSBackgroundTask) {
+      return true;
+    }
+    WidgetsFlutterBinding.ensureInitialized();
+    final ProviderContainer container = ProviderContainer();
+    try {
+      await container.read(llmDigestOrchestratorProvider).runScheduledDigest();
+      return true;
+    } finally {
+      container.dispose();
+    }
+  });
 }
 
-class RelationshipSaverApp extends ConsumerWidget {
-  const RelationshipSaverApp({super.key});
-
-  @override
-  Widget build(BuildContext context, WidgetRef ref) {
-    final AsyncValue<AuthSession?> sessionState = ref.watch(
-      sessionControllerProvider,
-    );
-
-    return MaterialApp(
-      title: 'Relationship Saver',
-      debugShowCheckedModeBanner: false,
-      theme: AppTheme.light(),
-      home: Scaffold(
-        body: sessionState.when(
-          data: (session) => session == null
-              ? const SignInView()
-              : const WhatsAppShareListener(
-                  child: ReminderNotificationListener(
-                    child: SyncBackgroundRunner(child: AppShell()),
-                  ),
-                ),
-          loading: () => const Center(child: CircularProgressIndicator()),
-          error: (Object error, StackTrace stackTrace) => const SignInView(),
-        ),
-      ),
-    );
+Future<void> main() async {
+  WidgetsFlutterBinding.ensureInitialized();
+  if (_supportsWorkmanagerPlatform()) {
+    await Workmanager().initialize(llmDigestCallbackDispatcher);
   }
+
+  final SentryInit sentry = SentryInit();
+  await sentry.initialize(
+    appRunner: () {
+      runApp(
+        ProviderScope(
+          overrides: [sentryInitProvider.overrideWithValue(sentry)],
+          child: const RelationshipSaverApp(),
+        ),
+      );
+    },
+  );
+}
+
+bool _supportsWorkmanagerPlatform() {
+  if (kIsWeb) {
+    return false;
+  }
+  return defaultTargetPlatform == TargetPlatform.iOS ||
+      defaultTargetPlatform == TargetPlatform.android;
 }