feat(admin): 添加提示词批量删除和定时同步功能

- 后端新增批量删除提示词接口和实现
- 前端管理页面添加多选和批量删除功能
- 添加定时同步GitHub远程提示词源功能
- 新增系统设置中的提示词同步配置选项
- 更新文档说明新的批量操作和定时同步功能
- 添加相关的测试用例和依赖库

handler/admin.go

@@ -13,6 +13,10 @@ type adminSyncRequest struct {
 	Category string `json:"category"`
 }
 
+type adminBatchDeleteRequest struct {
+	IDs []string `json:"ids"`
+}
+
 func AdminPromptCategories(w http.ResponseWriter, r *http.Request) {
 	OK(w, service.ListPromptCategories())
 }
@@ -45,6 +49,16 @@ func AdminDeletePrompt(w http.ResponseWriter, r *http.Request, id string) {
 	OK(w, true)
 }
 
+func AdminDeletePrompts(w http.ResponseWriter, r *http.Request) {
+	var request adminBatchDeleteRequest
+	_ = json.NewDecoder(r.Body).Decode(&request)
+	if err := service.DeletePrompts(request.IDs); err != nil {
+		FailError(w, err)
+		return
+	}
+	OK(w, true)
+}
+
 func AdminSyncPromptCategories(w http.ResponseWriter, r *http.Request) {
 	var request adminSyncRequest
 	_ = json.NewDecoder(r.Body).Decode(&request)