сборка: APK (Android) + Linux Desktop

- Исправлены ошибки Flutter анализа (withOpacity, pbkdf2, импорты)
- Упрощён pubspec.yaml (только нужные зависимости)
- Android APK собран: build/app/outputs/flutter-apk/app-release.apk (22MB)
- Linux Desktop собран: build/linux/x64/release/bundle/jam_client

Для Windows: кросс-компиляция невозможна с Linux.
Нужен Windows хост для flutter build windows.

client/lib/screens/chat_screen.dart

@@ -8,7 +8,6 @@ import '../services/api_service.dart';
 import '../services/theme_service.dart';
 import '../models/message.dart';
 import '../models/channel.dart';
-import '../models/guild.dart';
 import '../widgets/message_bubble.dart';
 import '../widgets/chat_input.dart';
 
@@ -28,7 +27,6 @@ class _ChatScreenState extends State<ChatScreen> {
   bool _atBottom = true;
 
   late Channel _channel;
-  late Guild _guild;
 
   @override
   void didChangeDependencies() {
@@ -36,7 +34,6 @@ class _ChatScreenState extends State<ChatScreen> {
     final args = ModalRoute.of(context)?.settings.arguments as Map?;
     if (args != null) {
       _channel = args['channel'] as Channel;
-      _guild = args['guild'] as Guild;
     }
   }
 
@@ -201,7 +198,7 @@ class _ChatScreenState extends State<ChatScreen> {
           Icon(
             _channel.isText ? Icons.tag : Icons.volume_up,
             size: 48,
-            color: ThemeService.textMuted.withValues(alpha: 0.5),
+            color: ThemeService.textMuted.withOpacity(0.5),
           ),
           const SizedBox(height: 12),
           Text(
@@ -226,7 +223,7 @@ class _ChatScreenState extends State<ChatScreen> {
           Text(
             'No messages yet. Start the conversation!',
             style: TextStyle(
-              color: ThemeService.textMuted.withValues(alpha: 0.8),
+              color: ThemeService.textMuted.withOpacity(0.8),
               fontSize: 14,
             ),
           ),