feat: 添加会话历史管理功能

- 在 AI 教练聊天界面中新增会话历史查看和选择功能，用户可以查看和选择之前的会话记录
- 实现会话删除功能，用户可以删除不需要的会话记录
- 优化历史会话的加载和展示，提升用户体验
- 更新相关样式以适应新功能的展示和交互

hooks/useCosUpload.ts

@@ -18,7 +18,7 @@ export function useCosUpload(defaultOptions?: UseCosUploadOptions) {
   }, []);
 
   const upload = useCallback(
-    async (file: { uri?: string; name?: string; type?: string; buffer?: any; blob?: Blob } | Blob | any, options?: UseCosUploadOptions) => {
+    async (file: { uri?: string; name?: string; type?: string; buffer?: any; blob?: Blob } | Blob | string | any, options?: UseCosUploadOptions) => {
       const finalOptions = { ...(defaultOptions || {}), ...(options || {}) };
       const extGuess = (() => {
         const name = (file && (file.name || (file as any).filename)) || '';
@@ -31,11 +31,29 @@ export function useCosUpload(defaultOptions?: UseCosUploadOptions) {
       setProgress(0);
       setUploading(true);
       try {
-        let body = (file as any)?.blob || (file as any)?.buffer || file;
-        // Expo ImagePicker 返回 { uri } 时，转换为 Blob
-        if (!body && (file as any)?.uri) {
+        let body: any = null;
+        // 1) 直接可用类型：Blob 或 string
+        if (typeof file === 'string') {
+          body = file;
+        } else if (typeof Blob !== 'undefined' && file instanceof Blob) {
+          body = file;
+        } else if ((file as any)?.blob && (typeof Blob === 'undefined' || (file as any).blob instanceof Blob || (file as any).blob?._data)) {
+          // 2) 已提供 blob 字段
+          body = (file as any).blob;
+        } else if ((file as any)?.buffer) {
+          // 3) ArrayBuffer/TypedArray -> Blob
+          const buffer = (file as any).buffer;
+          body = new Blob([buffer], { type: (file as any)?.type || finalOptions.contentType || 'application/octet-stream' });
+        } else if ((file as any)?.uri) {
+          // 4) Expo ImagePicker/文件：必须先转 Blob
           const resp = await fetch((file as any).uri);
           body = await resp.blob();
+        } else {
+          // 兜底：尝试直接作为字符串，否则抛错
+          if (file && (typeof file === 'object')) {
+            throw new Error('无效的上传体：请提供 Blob/String，或包含 uri 的对象');
+          }
+          body = file;
         }
         const res = await uploadWithRetry({
           key,