feat: Windows support - auto-update system + proper app icon

- PowerShell silent installer with UAC elevation
- Smart asset detection (x64 priority for .exe)
- Cross-platform restart after update
- Auto-check updates on launch (5 sec delay)
- Multi-layer .ico with 6 sizes (16-256px)
- Windows build documentation added

lib/bootstrap.dart

@@ -14,6 +14,7 @@ import 'package:umbrix/core/preferences/general_preferences.dart';
 import 'package:umbrix/core/preferences/preferences_migration.dart';
 import 'package:umbrix/core/preferences/preferences_provider.dart';
 import 'package:umbrix/features/app/widget/app.dart';
+import 'package:umbrix/features/app_update/notifier/app_update_notifier.dart';
 import 'package:umbrix/features/auto_start/notifier/auto_start_notifier.dart';
 import 'package:umbrix/features/common/custom_splash_screen.dart';
 import 'package:umbrix/features/deep_link/notifier/deep_link_notifier.dart';
@@ -153,6 +154,13 @@ Future<void> _performBootstrap(
       () => container.read(systemTrayNotifierProvider.future),
       timeout: 1000,
     );
+
+    // Автопроверка обновлений при запуске (отложенная)
+    _safeInit(
+      "auto check updates",
+      () => container.read(appUpdateNotifierProvider.notifier).checkSilently(),
+      timeout: 5000,
+    );
   }
 
   if (Platform.isAndroid) {