feat(settings): add manual update check

lib/core/utils/update_checker.dart

@@ -22,6 +22,22 @@ class AppUpdateInfo {
   });
 }
 
+enum UpdateCheckStatus { updateAvailable, upToDate, failed }
+
+class UpdateCheckResult {
+  final UpdateCheckStatus status;
+  final AppUpdateInfo? update;
+
+  const UpdateCheckResult._(this.status, [this.update]);
+
+  const UpdateCheckResult.updateAvailable(AppUpdateInfo update)
+    : this._(UpdateCheckStatus.updateAvailable, update);
+
+  const UpdateCheckResult.upToDate() : this._(UpdateCheckStatus.upToDate);
+
+  const UpdateCheckResult.failed() : this._(UpdateCheckStatus.failed);
+}
+
 abstract class UpdateChecker {
   static const String _owner = 'KometTeam';
   static const String _repo = 'Komet';
@@ -96,6 +112,21 @@ abstract class UpdateChecker {
     return update;
   }
 
+  /// Runs a user-initiated check without applying the automatic-check interval
+  /// or the "skip this version" preference.
+  static Future<UpdateCheckResult> checkNow() async {
+    try {
+      final update = await fetchLatest();
+      final prefs = await SharedPreferences.getInstance();
+      await prefs.setInt(_lastCheckKey, DateTime.now().millisecondsSinceEpoch);
+      return update == null
+          ? const UpdateCheckResult.upToDate()
+          : UpdateCheckResult.updateAvailable(update);
+    } catch (_) {
+      return const UpdateCheckResult.failed();
+    }
+  }
+
   static Future<void> skip(String tag) async {
     final prefs = await SharedPreferences.getInstance();
     await prefs.setString(_skippedTagKey, tag);
@@ -117,22 +148,25 @@ abstract class UpdateChecker {
       final resp = await req.close().timeout(_timeout);
       if (resp.statusCode != HttpStatus.ok) {
         await resp.drain<void>();
-        return null;
+        throw HttpException(
+          'GitHub returned HTTP ${resp.statusCode}',
+          uri: uri,
+        );
       }
       final body = await resp
           .transform(const Utf8Decoder())
           .join()
           .timeout(_timeout);
       final decoded = jsonDecode(body);
-      if (decoded is! List) return null;
+      if (decoded is! List) {
+        throw const FormatException('Invalid GitHub releases response');
+      }
       for (final entry in decoded) {
         if (entry is! Map) continue;
         if (entry['draft'] == true) continue;
         return entry.cast<String, dynamic>();
       }
       return null;
-    } catch (_) {
-      return null;
     } finally {
       client.close(force: true);
     }

lib/frontend/screens/profile/settings_tab.dart

@@ -9,6 +9,7 @@ import '../../../core/config/komet_settings.dart';
 import '../../../core/config/app_show_extra_info.dart';
 import '../../../core/storage/app_database.dart';
 import '../../../core/utils/format.dart';
+import '../../../core/utils/update_checker.dart';
 import '../../../l10n/app_localizations.dart';
 import '../../../main.dart';
 import '../../widgets/avatar_history_screen.dart';
@@ -19,6 +20,7 @@ import '../../widgets/settings_card.dart';
 import '../../widgets/sheet_helpers.dart';
 import '../../widgets/small_spinner.dart';
 import '../../widgets/custom_notification.dart';
+import '../../widgets/update_dialog.dart';
 import '../auth/login_screen.dart';
 import '../auth/proxy_settings_sheet.dart';
 import '../../../core/config/app_digital_id_mode.dart';
@@ -49,6 +51,7 @@ class _SettingsTabState extends State<SettingsTab> {
   bool _isPhoneVisible = false;
   String? _appVersionLabel;
   bool _debugMenuVisible = false;
+  bool _isCheckingForUpdates = false;
   int _versionSecretTapCount = 0;
   Timer? _versionSecretTapResetTimer;
   StreamSubscription? _profileUpdateSub;
@@ -105,6 +108,33 @@ class _SettingsTabState extends State<SettingsTab> {
     });
   }
 
+  Future<void> _checkForUpdates() async {
+    if (_isCheckingForUpdates) return;
+    setState(() => _isCheckingForUpdates = true);
+
+    final result = await UpdateChecker.checkNow();
+    if (!mounted) return;
+    setState(() => _isCheckingForUpdates = false);
+
+    switch (result.status) {
+      case UpdateCheckStatus.updateAvailable:
+        await showUpdateDialog(context, result.update!);
+        return;
+      case UpdateCheckStatus.upToDate:
+        showCustomNotification(
+          context,
+          AppLocalizations.of(context)!.updateUpToDate,
+        );
+        return;
+      case UpdateCheckStatus.failed:
+        showCustomNotification(
+          context,
+          AppLocalizations.of(context)!.updateCheckFailed,
+        );
+        return;
+    }
+  }
+
   Future<void> _openCloudStorage(BuildContext context) async {
     final cs = Theme.of(context).colorScheme;
     final ok = await showInfoActionSheet(
@@ -221,6 +251,7 @@ class _SettingsTabState extends State<SettingsTab> {
   @override
   Widget build(BuildContext context) {
     final cs = Theme.of(context).colorScheme;
+    final l10n = AppLocalizations.of(context)!;
 
     if (_profile == null) {
       return const Center(child: SmallSpinner(size: 36));
@@ -444,6 +475,13 @@ class _SettingsTabState extends State<SettingsTab> {
                 child: _buildSection(
                   context,
                   items: [
+                    _SettingsItem(
+                      icon: Symbols.system_update,
+                      label: _isCheckingForUpdates
+                          ? l10n.updateChecking
+                          : l10n.updateCheck,
+                      onTap: _isCheckingForUpdates ? null : _checkForUpdates,
+                    ),
                     _SettingsItem(
                       leading: Image.asset(
                         'assets/komet.png',

lib/l10n/app_en.arb

@@ -903,5 +903,9 @@
   "updateLater": "Later",
   "updateSkip": "Skip",
   "updateDownloading": "Downloading update…",
-  "updateDownloadFailed": "Failed to download the update"
+  "updateDownloadFailed": "Failed to download the update",
+  "updateCheck": "Check for updates",
+  "updateChecking": "Checking for updates…",
+  "updateUpToDate": "You have the latest version",
+  "updateCheckFailed": "Couldn't check for updates. Try again later"
 }

lib/l10n/app_localizations.dart

@@ -4021,6 +4021,30 @@ abstract class AppLocalizations {
   /// In en, this message translates to:
   /// **'Failed to download the update'**
   String get updateDownloadFailed;
+
+  /// No description provided for @updateCheck.
+  ///
+  /// In en, this message translates to:
+  /// **'Check for updates'**
+  String get updateCheck;
+
+  /// No description provided for @updateChecking.
+  ///
+  /// In en, this message translates to:
+  /// **'Checking for updates…'**
+  String get updateChecking;
+
+  /// No description provided for @updateUpToDate.
+  ///
+  /// In en, this message translates to:
+  /// **'You have the latest version'**
+  String get updateUpToDate;
+
+  /// No description provided for @updateCheckFailed.
+  ///
+  /// In en, this message translates to:
+  /// **'Couldn\'t check for updates. Try again later'**
+  String get updateCheckFailed;
 }
 
 class _AppLocalizationsDelegate

lib/l10n/app_localizations_en.dart

@@ -2084,4 +2084,17 @@ class AppLocalizationsEn extends AppLocalizations {
 
   @override
   String get updateDownloadFailed => 'Failed to download the update';
+
+  @override
+  String get updateCheck => 'Check for updates';
+
+  @override
+  String get updateChecking => 'Checking for updates…';
+
+  @override
+  String get updateUpToDate => 'You have the latest version';
+
+  @override
+  String get updateCheckFailed =>
+      'Couldn\'t check for updates. Try again later';
 }

lib/l10n/app_localizations_ru.dart

@@ -2095,4 +2095,17 @@ class AppLocalizationsRu extends AppLocalizations {
 
   @override
   String get updateDownloadFailed => 'Не удалось скачать обновление';
+
+  @override
+  String get updateCheck => 'Проверить обновление';
+
+  @override
+  String get updateChecking => 'Проверяем обновления…';
+
+  @override
+  String get updateUpToDate => 'Установлена актуальная версия';
+
+  @override
+  String get updateCheckFailed =>
+      'Не удалось проверить обновления. Повторите позже';
 }

lib/l10n/app_ru.arb

@@ -685,5 +685,9 @@
   "updateLater": "Позже",
   "updateSkip": "Пропустить",
   "updateDownloading": "Загрузка обновления…",
-  "updateDownloadFailed": "Не удалось скачать обновление"
+  "updateDownloadFailed": "Не удалось скачать обновление",
+  "updateCheck": "Проверить обновление",
+  "updateChecking": "Проверяем обновления…",
+  "updateUpToDate": "Установлена актуальная версия",
+  "updateCheckFailed": "Не удалось проверить обновления. Повторите позже"
 }