feat(app): смена сервера API и очистка данных устройства при выходе

Адрес бэкенда хранится в shared_preferences и читается до runApp; switchApiBaseUrl сбрасывает токены и кэш старого сервера. Выход стирает refresh-токен и sqlite-кэш ответов. Экран настроек переделан под разделы.

app/lib/core/cache/cache_interceptor.dart

@@ -28,7 +28,10 @@ class CacheInterceptor extends Interceptor {
   };
 
   @override
-  void onResponse(Response<dynamic> response, ResponseInterceptorHandler handler) {
+  void onResponse(
+    Response<dynamic> response,
+    ResponseInterceptorHandler handler,
+  ) {
     if (response.requestOptions.method == 'GET' && response.statusCode == 200) {
       // Never block the UI on the write: the caller already has its data.
       unawaited(_db.put(requestKey(response.requestOptions), response.data));
@@ -37,8 +40,12 @@ class CacheInterceptor extends Interceptor {
   }
 
   @override
-  Future<void> onError(DioException err, ErrorInterceptorHandler handler) async {
-    if (err.requestOptions.method != 'GET' || !_offlineTypes.contains(err.type)) {
+  Future<void> onError(
+    DioException err,
+    ErrorInterceptorHandler handler,
+  ) async {
+    if (err.requestOptions.method != 'GET' ||
+        !_offlineTypes.contains(err.type)) {
       return handler.next(err);
     }
     final cached = await _db.get(requestKey(err.requestOptions));
@@ -56,7 +63,8 @@ class CacheInterceptor extends Interceptor {
   /// `path?sorted=query` — deliberately excludes the host, so switching the API
   /// origin (dev vs. prod) does not orphan a device's cache.
   static String requestKey(RequestOptions options) {
-    final params = options.queryParameters.entries.toList()..sort((a, b) => a.key.compareTo(b.key));
+    final params = options.queryParameters.entries.toList()
+      ..sort((a, b) => a.key.compareTo(b.key));
     final query = params.map((e) => '${e.key}=${e.value}').join('&');
     return '${options.path}?$query';
   }

app/lib/core/cache/cached.dart

@@ -15,7 +15,8 @@ extension CachedResponseX<T> on Response<T> {
   /// Wraps this response's data with the staleness [CacheInterceptor] recorded
   /// in `extra['fetchedAt']`. A provider that wants offline support returns
   /// `r.cached` instead of `r.data!`.
-  Cached<T> get cached => Cached(data as T, fetchedAt: extra['fetchedAt'] as DateTime?);
+  Cached<T> get cached =>
+      Cached(data as T, fetchedAt: extra['fetchedAt'] as DateTime?);
 }
 
 /// The oldest of several fetch times, or null if none of them is stale.

app/lib/core/cache/response_cache.dart

@@ -38,7 +38,8 @@ class ResponseCacheDatabase extends _$ResponseCacheDatabase {
 
   /// Replaces whatever was cached for [requestKey] — one row per endpoint+params,
   /// never a history.
-  Future<void> put(String requestKey, Object? body) => into(cachedResponses).insertOnConflictUpdate(
+  Future<void> put(String requestKey, Object? body) =>
+      into(cachedResponses).insertOnConflictUpdate(
         CachedResponsesCompanion.insert(
           requestKey: requestKey,
           body: jsonEncode(body),
@@ -46,6 +47,9 @@ class ResponseCacheDatabase extends _$ResponseCacheDatabase {
         ),
       );
 
+  /// Drops every cached body — on sign-out, so the next account (or nobody) never sees them.
+  Future<void> clear() => delete(cachedResponses).go();
+
   /// The body last stored for [requestKey], or null if this endpoint+params was
   /// never fetched successfully on this device.
   Future<CacheEntry?> get(String requestKey) async {
@@ -63,9 +67,9 @@ class ResponseCacheDatabase extends _$ResponseCacheDatabase {
 /// the compiled assets it loads there (regenerate with `just app-web-assets`
 /// whenever the `drift`/`sqlite3` package versions change).
 QueryExecutor _openConnection() => driftDatabase(
-      name: 'response_cache',
-      web: DriftWebOptions(
-        sqlite3Wasm: Uri.parse('sqlite3.wasm'),
-        driftWorker: Uri.parse('drift_worker.js'),
-      ),
-    );
+  name: 'response_cache',
+  web: DriftWebOptions(
+    sqlite3Wasm: Uri.parse('sqlite3.wasm'),
+    driftWorker: Uri.parse('drift_worker.js'),
+  ),
+);

app/lib/core/cache/response_cache_provider.dart

@@ -0,0 +1,11 @@
+import 'package:flutter_riverpod/flutter_riverpod.dart';
+
+import 'response_cache.dart';
+
+/// One sqlite-backed cache of the last successful GET per endpoint+params,
+/// shared by every screen. See `docs/ai/offline-cache.md`.
+final responseCacheDbProvider = Provider<ResponseCacheDatabase>((ref) {
+  final db = ResponseCacheDatabase();
+  ref.onDispose(db.close);
+  return db;
+});