feat(s2a): Add S2A configuration profiles management system

- Add new `/api/s2a/profiles` endpoint supporting GET, POST, DELETE operations
- Create `s2a_profiles` database table with fields for API configuration, concurrency, priority, group IDs, and proxy settings
- Implement database methods: `GetS2AProfiles()`, `AddS2AProfile()`, `DeleteS2AProfile()`
- Add S2AProfile struct to database models with JSON serialization support
- Implement profile management UI in S2AConfig page with save, load, and delete functionality
- Add profile list display with ability to apply saved configurations
- Add S2AProfile type definition to frontend types
- Enable users to save and reuse S2A configurations as presets for faster setup

backend/cmd/main.go

@@ -123,6 +123,7 @@ func startServer(cfg *config.Config) {
 	mux.HandleFunc("/api/s2a/proxy/", api.CORS(handleS2AProxy))                     // 通配代理
 	mux.HandleFunc("/api/s2a/clean-errors", api.CORS(api.HandleCleanErrorAccounts)) // 清理错误账号
 	mux.HandleFunc("/api/s2a/cleaner/settings", api.CORS(handleCleanerSettings))    // 清理服务设置
+	mux.HandleFunc("/api/s2a/profiles", api.CORS(handleS2AProfiles))                // S2A 配置预设管理
 
 	// 统计 API
 	mux.HandleFunc("/api/stats/max-rpm", api.CORS(api.HandleGetMaxRPM)) // 今日最高 RPM
@@ -1138,6 +1139,62 @@ func handleCleanerSettings(w http.ResponseWriter, r *http.Request) {
 	}
 }
 
+// handleS2AProfiles GET/POST/DELETE /api/s2a/profiles
+func handleS2AProfiles(w http.ResponseWriter, r *http.Request) {
+	if database.Instance == nil {
+		api.Error(w, http.StatusInternalServerError, "数据库未初始化")
+		return
+	}
+
+	switch r.Method {
+	case http.MethodGet:
+		profiles, err := database.Instance.GetS2AProfiles()
+		if err != nil {
+			api.Error(w, http.StatusInternalServerError, fmt.Sprintf("获取配置预设失败: %v", err))
+			return
+		}
+		// 确保 group_ids 解析为 JSON
+		// (数据库层返回的是 JSON string, 这里前端可以直接用，或者我们在 Go 里转一下)
+		// 由于 database.S2AProfile 定义 GroupIDs 为 string，我们直接返回即可，前端解析
+		api.Success(w, profiles)
+
+	case http.MethodPost:
+		var p database.S2AProfile
+		if err := json.NewDecoder(r.Body).Decode(&p); err != nil {
+			api.Error(w, http.StatusBadRequest, "请求格式错误")
+			return
+		}
+		if p.Name == "" {
+			api.Error(w, http.StatusBadRequest, "配置名称不能为空")
+			return
+		}
+
+		id, err := database.Instance.AddS2AProfile(p)
+		if err != nil {
+			api.Error(w, http.StatusInternalServerError, fmt.Sprintf("保存配置预设失败: %v", err))
+			return
+		}
+		p.ID = id
+		api.Success(w, p)
+
+	case http.MethodDelete:
+		idStr := r.URL.Query().Get("id")
+		id, err := strconv.ParseInt(idStr, 10, 64)
+		if err != nil {
+			api.Error(w, http.StatusBadRequest, "无效的 ID")
+			return
+		}
+		if err := database.Instance.DeleteS2AProfile(id); err != nil {
+			api.Error(w, http.StatusInternalServerError, fmt.Sprintf("删除配置预设失败: %v", err))
+			return
+		}
+		api.Success(w, map[string]string{"message": "已删除"})
+
+	default:
+		api.Error(w, http.StatusMethodNotAllowed, "不支持的方法")
+	}
+}
+
 // handleProxyTest POST /api/proxy/test - 测试代理连接
 func handleProxyTest(w http.ResponseWriter, r *http.Request) {
 	if r.Method != http.MethodPost {