Implement clearing user data on logout

lib/core/services/storage_service.dart

@@ -104,9 +104,32 @@ class StorageService {
     return _secureStorage.write(key: key.name, value: value);
   }
 
-  /// Clears the JWT token from secure storage.
-  Future<void> clearToken() {
-    return writeSecure(SecureStorageKey.jwt, null);
+  /// Clears all user data except URL and email.
+  ///
+  /// Called on logout to ensure a clean state for the next user,
+  /// while preserving server URL and email for convenience.
+  Future<void> clearAllUserData() async {
+    // Clear JWT token
+    await writeSecure(SecureStorageKey.jwt, null);
+
+    // Clear all Hive boxes
+    final sheetAccessTimesBox = await Hive.openBox(_sheetAccessTimesBox);
+    await sheetAccessTimesBox.clear();
+
+    final configBox = await Hive.openBox(_configBox);
+    await configBox.clear();
+
+    final changeQueueBox = await Hive.openBox(_changeQueueBox);
+    await changeQueueBox.clear();
+
+    final annotationsBox = await Hive.openBox(_annotationsBox);
+    await annotationsBox.clear();
+
+    final sheetsBox = await Hive.openBox(_sheetsBox);
+    await sheetsBox.clear();
+
+    final pendingAnnotationsBox = await Hive.openBox(_pendingAnnotationsBox);
+    await pendingAnnotationsBox.clear();
   }
 
   // ---------------------------------------------------------------------------