Port Komet UI improvements and implement IKAR ghost mode

Adapt video editing, decrypted message actions, custom themes and gestures from PR 166. Track visible server presence per session and preserve delivery for invisible clients.

test/custom_theme_screen_test.dart

@@ -0,0 +1,117 @@
+import 'dart:io';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:path_provider_platform_interface/path_provider_platform_interface.dart';
+import 'package:ikar/core/config/app_wallpaper_tint.dart';
+import 'package:ikar/core/storage/app_database.dart';
+import 'package:ikar/core/storage/chat_wallpaper_store.dart';
+import 'package:ikar/core/utils/haptics.dart';
+import 'package:ikar/frontend/screens/profile/custom_gradient_editor_screen.dart';
+import 'package:ikar/frontend/screens/profile/theme_settings_screen.dart';
+import 'package:ikar/l10n/app_localizations.dart';
+import 'package:ikar/main.dart' show api;
+import 'package:shared_preferences/shared_preferences.dart';
+
+class _Paths extends PathProviderPlatform {
+  _Paths(this.path);
+  final String path;
+  @override
+  Future<String?> getApplicationSupportPath() async => path;
+  @override
+  Future<String?> getApplicationDocumentsPath() async => path;
+}
+
+void main() {
+  TestWidgetsFlutterBinding.ensureInitialized();
+  testWidgets(
+    'custom theme edits the global gradient and keeps chat overrides',
+    (tester) async {
+      final previousPaths = PathProviderPlatform.instance;
+      late Directory dir;
+      await tester.runAsync(() async {
+        api.state;
+        dir = await Directory.systemTemp.createTemp('ikar-theme-test-');
+        PathProviderPlatform.instance = _Paths(dir.path);
+        SharedPreferences.setMockInitialValues({});
+        Haptics.enabled = false;
+        await AppWallpaperTint.load();
+        await AppDatabase.init();
+        await AppDatabase.saveProfile(ProfileData.stub(42));
+        await AppDatabase.setActiveAccount(42);
+        await ChatWallpaperStore.instance.load();
+        await ChatWallpaperStore.instance.setTheme(
+          42,
+          7,
+          'synthetic-chat-theme',
+        );
+      });
+      addTearDown(() async {
+        await api.dispose();
+        await AppDatabase.close();
+        PathProviderPlatform.instance = previousPaths;
+        Haptics.enabled = true;
+        await dir.delete(recursive: true);
+      });
+      await tester.pumpWidget(
+        MaterialApp(
+          locale: const Locale('ru'),
+          localizationsDelegates: AppLocalizations.localizationsDelegates,
+          supportedLocales: AppLocalizations.supportedLocales,
+          home: const ThemeSettingsScreen(),
+        ),
+      );
+      await tester.runAsync(
+        () => Future<void>.delayed(const Duration(milliseconds: 100)),
+      );
+      await tester.pumpAndSettle();
+      await tester.tap(find.text('Собственная тема'));
+      await tester.pumpAndSettle();
+      expect(AppWallpaperTint.current.value, isTrue);
+      expect(find.text('Настроить'), findsOneWidget);
+      await tester.tap(find.text('Настроить'));
+      await tester.pumpAndSettle();
+      expect(find.byType(CustomGradientEditorScreen), findsOneWidget);
+      final editorContext = tester.element(
+        find.byType(CustomGradientEditorScreen),
+      );
+      Navigator.of(editorContext).pop(
+        const CustomGradientResult(
+          colors: [Colors.red, Colors.blue],
+          animated: false,
+          rotation: 0.7,
+        ),
+      );
+      await tester.runAsync(
+        () => Future<void>.delayed(const Duration(milliseconds: 100)),
+      );
+      await tester.pumpAndSettle();
+      final wallpaper = ChatWallpaperStore.instance.get(
+        42,
+        kGlobalWallpaperChatId,
+      )!;
+      expect(wallpaper.gradientColors!.map((color) => color.toARGB32()), [
+        Colors.red.toARGB32(),
+        Colors.blue.toARGB32(),
+      ]);
+      expect(wallpaper.gradientRotation, 0.7);
+      expect(
+        ChatWallpaperStore.instance.get(42, 7)!.themeId,
+        'synthetic-chat-theme',
+      );
+      final restored = ChatWallpaperStore.forTesting();
+      await tester.runAsync(restored.load);
+      expect(
+        restored
+            .get(42, kGlobalWallpaperChatId)!
+            .gradientColors!
+            .map((color) => color.toARGB32()),
+        [Colors.red.toARGB32(), Colors.blue.toARGB32()],
+      );
+      await tester.tap(find.text('Системная'));
+      await tester.pumpAndSettle();
+      expect(AppWallpaperTint.current.value, isFalse);
+      expect(restored.get(42, kGlobalWallpaperChatId), isNotNull);
+      await tester.pumpWidget(const SizedBox.shrink());
+    },
+  );
+}