refactor(storage): 迁移 AsyncStorage 至 expo-sqlite/kv-store

- 统一替换所有 @react-native-async-storage/async-storage 导入为自定义 kvStore
- 新增 kvStore.ts 封装 expo-sqlite/kv-store，保持与 AsyncStorage 完全兼容
- 新增同步读写方法，提升性能
- 引入 expo-sqlite 依赖并更新 lock 文件

BREAKING CHANGE: 移除 @react-native-async-storage/async-storage 依赖，需重新安装依赖并清理旧数据

services/aiCoachSession.ts

@@ -1,4 +1,4 @@
-import AsyncStorage from '@react-native-async-storage/async-storage';
+import AsyncStorage from '@/utils/kvStore';
 
 export type AiCoachChatMessage = {
   id: string;