feat: Implement TTS playback store and enhance reading progress synchronization

- Added ReaderTtsPlaybackStore to manage TTS start requests with a maximum of 4 pending requests.
- Updated app configuration to use a production API URL.
- Enhanced BookmarkModel to infer type when not provided by the API for backward compatibility.
- Introduced methods in LocalStore for saving, loading, and clearing the last route path.
- Implemented syncProgress method in BookshelfNotifier to update reading progress and bookmarks from the server.
- Modified ReaderScreen to handle chapter navigation and TTS playback more effectively, including auto-start logic.
- Updated TtsPlayerWidget to accept additional parameters for chapter navigation.
- Enhanced TtsNotifier to handle new parameters for TTS requests and manage playback state.
- Improved SplashScreen to restore the last visited route after splash screen display.

lib/core/storage/local_store.dart

@@ -16,6 +16,7 @@ class LocalStore {
   static const _kProgressChapterId = 'progress_chapter_id_';
   static const _kProgressChapterNum = 'progress_chapter_num_';
   static const _kProgressOffset = 'progress_offset_';
+  static const _kLastRoutePath = 'last_route_path';
 
   // ── Reading settings ──────────────────────────────────────────────────────
 
@@ -86,6 +87,27 @@ class LocalStore {
       'scrollOffset': prefs.getDouble('$_kProgressOffset$novelId') ?? 0.0,
     };
   }
+
+  // ── Last route restore (cold start after process reclaim) ───────────────
+
+  Future<void> saveLastRoutePath(String path) async {
+    final normalized = path.trim();
+    if (normalized.isEmpty || normalized == '/') return;
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.setString(_kLastRoutePath, normalized);
+  }
+
+  Future<String?> loadLastRoutePath() async {
+    final prefs = await SharedPreferences.getInstance();
+    final value = prefs.getString(_kLastRoutePath)?.trim();
+    if (value == null || value.isEmpty) return null;
+    return value;
+  }
+
+  Future<void> clearLastRoutePath() async {
+    final prefs = await SharedPreferences.getInstance();
+    await prefs.remove(_kLastRoutePath);
+  }
 }
 
 final localStoreProvider = Provider<LocalStore>((_) => LocalStore());