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/chat/data/models/ag_ui_event.g.dart

@@ -6,9 +6,6 @@ part of 'ag_ui_event.dart';
 // JsonSerializableGenerator
 // **************************************************************************
 
-AgUiEvent _$AgUiEventFromJson(Map<String, dynamic> json) =>
-    AgUiEvent(type: $enumDecode(_$AgUiEventTypeEnumMap, json['type']));
-
 Map<String, dynamic> _$AgUiEventToJson(AgUiEvent instance) => <String, dynamic>{
   'type': _$AgUiEventTypeEnumMap[instance.type]!,
 };
@@ -29,12 +26,6 @@ const _$AgUiEventTypeEnumMap = {
   AgUiEventType.unknown: 'unknown',
 };
 
-UnknownAgUiEvent _$UnknownAgUiEventFromJson(Map<String, dynamic> json) =>
-    UnknownAgUiEvent(rawJson: json['rawJson'] as Map<String, dynamic>);
-
-Map<String, dynamic> _$UnknownAgUiEventToJson(UnknownAgUiEvent instance) =>
-    <String, dynamic>{'rawJson': instance.rawJson};
-
 RunStartedEvent _$RunStartedEventFromJson(Map<String, dynamic> json) =>
     RunStartedEvent(
       threadId: json['threadId'] as String,