fix(urlvalidator): 移除 ValidateURLFormat 返回值的末尾斜杠

修复 API Key 账号 base_url 末尾带斜杠时导致的双斜杠问题

backend/internal/util/urlvalidator/validator.go

@@ -46,7 +46,7 @@ func ValidateURLFormat(raw string, allowInsecureHTTP bool) (string, error) {
 		}
 	}
 
-	return trimmed, nil
+	return strings.TrimRight(trimmed, "/"), nil
 }
 
 func ValidateHTTPSURL(raw string, opts ValidationOptions) (string, error) {