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/settings_provider.dart

@@ -0,0 +1,35 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+import 'package:shared_preferences/shared_preferences.dart';
+
+const _kServerUrl = 'server_url';
+
+final sharedPreferencesProvider = Provider<SharedPreferences>((ref) {
+  throw UnimplementedError('Override in ProviderScope');
+});
+
+final cookiesPathProvider = Provider<String>((ref) {
+  throw UnimplementedError('Override in ProviderScope');
+});
+
+final serverUrlProvider = StateNotifierProvider<ServerUrlNotifier, String?>((ref) {
+  final prefs = ref.watch(sharedPreferencesProvider);
+  return ServerUrlNotifier(prefs);
+});
+
+class ServerUrlNotifier extends StateNotifier<String?> {
+  final SharedPreferences _prefs;
+
+  ServerUrlNotifier(this._prefs) : super(_prefs.getString(_kServerUrl));
+
+  Future<void> setUrl(String url) async {
+    // Strip trailing slash
+    final clean = url.endsWith('/') ? url.substring(0, url.length - 1) : url;
+    await _prefs.setString(_kServerUrl, clean);
+    state = clean;
+  }
+
+  Future<void> clear() async {
+    await _prefs.remove(_kServerUrl);
+    state = null;
+  }
+}