Support IPv4 HTTP public gateway entries

backend/internal/api/tls.go

@@ -169,7 +169,7 @@ func (s *Server) setTLSDomain(c *gin.Context) {
 	status := tlsservice.Status()
 	newBase := tlsservice.PublicBaseURL(scheme, strings.ToLower(strings.TrimSpace(req.Domain)), port)
 	if newBase == "" || port < 0 || port > 65535 {
-		c.JSON(http.StatusBadRequest, gin.H{"error": "公网域名、协议或端口无效"})
+		c.JSON(http.StatusBadRequest, gin.H{"error": "公网地址、协议或端口无效；IPv4 地址仅支持 HTTP"})
 		return
 	}
 	// The Go listener cannot be rebound in place; Nginx owns its own sockets.