feat: 添加首页图片选择功能（拍照/相册）

apps/test/features/chat/ag_ui_service_test.dart

@@ -1,6 +1,7 @@
 import 'dart:convert';
 
 import 'package:flutter_test/flutter_test.dart';
+import 'package:image_picker/image_picker.dart';
 import 'package:social_app/core/api/mock_api_client.dart';
 import 'package:social_app/features/chat/data/ai/ai_decision_engine.dart';
 import 'package:social_app/features/chat/data/models/ag_ui_event.dart';
@@ -12,7 +13,7 @@ class TestableAgUiService extends AgUiService {
   TestableAgUiService({super.onEvent});
 
   @override
-  Future<void> sendMessage(String content) async {
+  Future<void> sendMessage(String content, {List<XFile>? images}) async {
     await mockEventStream(content);
   }