feat: 添加好友功能并集成 LiteLLM 代理服务

- 新增好友搜索、添加、好友列表功能
- 集成 LiteLLM 代理服务及多模型定价配置
- 更新 iOS CocoaPods 配置
- 更新 .gitignore 和环境变量配置

.gitignore

@@ -178,8 +178,7 @@ __marimo__/
 # Flutter/Dart/Pub related
 **/doc/api/
 .dart_tool/
-.flutter-plugins
-.flutter-plugins-dependencies
+.dart_tool/flutter_build/
 **/generated_plugin_registrant.dart
 .packages
 .pub-preload-cache/
@@ -190,6 +189,9 @@ linked_*.ds
 unlinked.ds
 unlinked_spec.ds
 
+# IDE
+.idea/
+
 # Android related
 **/android/**/gradle-wrapper.jar
 .gradle/
@@ -200,6 +202,7 @@ unlinked_spec.ds
 **/android/**/GeneratedPluginRegistrant.java
 **/android/key.properties
 *.jks
+**/android/**/*.iml
 
 # iOS/XCode related
 **/ios/**/*.mode1v3
@@ -230,6 +233,9 @@ unlinked_spec.ds
 **/ios/Flutter/flutter_export_environment.sh
 **/ios/ServiceDefinitions.json
 **/ios/Runner/GeneratedPluginRegistrant.*
+**/ios/Podfile.lock
+**/ios/Runner.xcodeproj/
+**/ios/Runner.xcworkspace/
 
 # macOS
 **/Flutter/ephemeral/