feat: implement core backend for team owner management with SQLite, auto-add APIs, and a frontend owner list component.

backend/internal/api/auto_add.go

@@ -206,12 +206,21 @@ func getS2AAccountCount() (int, error) {
 	}
 
 	var result struct {
-		NormalAccounts int `json:"normal_accounts"`
+		Code    int    `json:"code"`
+		Message string `json:"message"`
+		Data    struct {
+			NormalAccounts int `json:"normal_accounts"`
+		} `json:"data"`
 	}
 
 	if err := decodeJSON(resp.Body, &result); err != nil {
 		return 0, err
 	}
 
-	return result.NormalAccounts, nil
+	// S2A 返回 code=0 表示成功
+	if result.Code != 0 {
+		return 0, fmt.Errorf("S2A 返回错误: %s", result.Message)
+	}
+
+	return result.Data.NormalAccounts, nil
 }