refactor(apps): simplify API layer by removing redundant wrapper classes

- Remove ApiClientWrapper and MockApiClientWrapper
- Simplify IApiClient interface
- Update dependency injection configuration
- Optimize calendar service and AG-UI chat models

apps/lib/features/calendar/data/services/mock_calendar_service.dart

@@ -1,4 +1,4 @@
-import 'package:social_app/core/config/env.dart';
+import 'package:social_app/core/api/i_api_client.dart';
 import '../models/schedule_item_model.dart';
 
 class MockCalendarService {
@@ -56,54 +56,50 @@ class MockCalendarService {
 }
 
 class CalendarService {
-  static final CalendarService _instance = CalendarService._internal();
-  factory CalendarService() => _instance;
-  CalendarService._internal();
+  final IApiClient? _apiClient;
+  final MockCalendarService _mock = MockCalendarService();
 
-  MockCalendarService get _mock => MockCalendarService();
+  CalendarService({IApiClient? apiClient}) : _apiClient = apiClient;
 
   List<ScheduleItemModel> getEventsForDay(DateTime date) {
-    if (Env.isMockApi) {
-      return _mock.getEventsForDay(date);
+    if (_apiClient != null) {
+      throw UnimplementedError('Real API not implemented');
     }
-    throw UnimplementedError('Real API not implemented');
+    return _mock.getEventsForDay(date);
   }
 
   List<ScheduleItemModel> getEventsForRange(DateTime start, DateTime end) {
-    if (Env.isMockApi) {
-      return _mock.getEventsForRange(start, end);
+    if (_apiClient != null) {
+      throw UnimplementedError('Real API not implemented');
     }
-    throw UnimplementedError('Real API not implemented');
+    return _mock.getEventsForRange(start, end);
   }
 
   ScheduleItemModel? getEventById(String id) {
-    if (Env.isMockApi) {
-      return _mock.getEventById(id);
+    if (_apiClient != null) {
+      throw UnimplementedError('Real API not implemented');
     }
-    throw UnimplementedError('Real API not implemented');
+    return _mock.getEventById(id);
   }
 
   void addEvent(ScheduleItemModel event) {
-    if (Env.isMockApi) {
-      _mock.addEvent(event);
-      return;
+    if (_apiClient != null) {
+      throw UnimplementedError('Real API not implemented');
     }
-    throw UnimplementedError('Real API not implemented');
+    _mock.addEvent(event);
   }
 
   void updateEvent(ScheduleItemModel event) {
-    if (Env.isMockApi) {
-      _mock.updateEvent(event);
-      return;
+    if (_apiClient != null) {
+      throw UnimplementedError('Real API not implemented');
     }
-    throw UnimplementedError('Real API not implemented');
+    _mock.updateEvent(event);
   }
 
   void deleteEvent(String id) {
-    if (Env.isMockApi) {
-      _mock.deleteEvent(id);
-      return;
+    if (_apiClient != null) {
+      throw UnimplementedError('Real API not implemented');
     }
-    throw UnimplementedError('Real API not implemented');
+    _mock.deleteEvent(id);
   }
 }

apps/lib/features/calendar/ui/screens/calendar_month_screen.dart

@@ -304,7 +304,7 @@ class _CalendarMonthScreenState extends State<CalendarMonthScreen> {
                         vertical: 2,
                       ),
                       decoration: BoxDecoration(
-                        color: color.withOpacity(0.2),
+                        color: color.withValues(alpha: 0.2),
                         borderRadius: BorderRadius.circular(4),
                       ),
                       child: Text(

apps/lib/features/calendar/ui/widgets/create_event_sheet.dart

@@ -368,7 +368,7 @@ class _CreateEventSheetState extends State<CreateEventSheet>
         Row(
           children: defaultColors.map((color) {
             final colorHex =
-                '#${color.value.toRadixString(16).substring(2).toUpperCase()}';
+                '#${color.toARGB32().toRadixString(16).substring(2).toUpperCase()}';
             final isSelected = _selectedColor == colorHex;
             return GestureDetector(
               onTap: () => setState(() => _selectedColor = colorHex),