Initial commit: Fabled Android app

Flutter Android client for FabledAssistant with:
- Session-cookie auth via persistent cookie jar (Dio + cookie_jar)
- OAuth/SSO login via in-app WebView (flutter_inappwebview)
- Notes: list, detail (markdown render), create/edit
- Tasks: list with status tabs, create/edit with priority
- Chat: SSE streaming bubbles, conversation management
- Quick Capture FAB for rapid note/task creation
- Settings screen (change server URL, logout)
- Android home screen widget → opens chat
- Riverpod state management, go_router navigation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/providers/auth_provider.dart

@@ -0,0 +1,40 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'api_client_provider.dart';
+
+enum AuthStatus { unknown, authenticated, unauthenticated }
+
+final authProvider = StateNotifierProvider<AuthNotifier, AuthStatus>((ref) {
+  return AuthNotifier(ref);
+});
+
+class AuthNotifier extends StateNotifier<AuthStatus> {
+  final Ref _ref;
+
+  AuthNotifier(this._ref) : super(AuthStatus.unknown);
+
+  Future<void> verify() async {
+    try {
+      final repo = _ref.read(authRepositoryProvider);
+      final ok = await repo.verify();
+      state = ok ? AuthStatus.authenticated : AuthStatus.unauthenticated;
+    } catch (_) {
+      state = AuthStatus.unauthenticated;
+    }
+  }
+
+  Future<void> login(String username, String password) async {
+    final repo = _ref.read(authRepositoryProvider);
+    await repo.login(username, password);
+    state = AuthStatus.authenticated;
+  }
+
+  Future<void> logout() async {
+    try {
+      final repo = _ref.read(authRepositoryProvider);
+      await repo.logout();
+    } finally {
+      state = AuthStatus.unauthenticated;
+    }
+  }
+}