feat: show current owner names and persist user and limit order (#576)

Resolve current forwarding-rule owner names by user ID. Add administrator-managed persistent user and speed-limit ordering, backup compatibility, and conflict recovery. Repair PostgreSQL explicit-ID import sequences transactionally.

Closes #574
Closes #575

go-backend/internal/http/handler/display_order.go

@@ -0,0 +1,45 @@
+package handler
+
+import (
+	"errors"
+	"go-backend/internal/http/response"
+	"go-backend/internal/store/repo"
+	"net/http"
+)
+
+func (h *Handler) userDisplayOrder(w http.ResponseWriter, r *http.Request) {
+	updateDisplayOrder(w, r, h.repo.UpdateUserDisplayOrder)
+}
+func (h *Handler) speedLimitDisplayOrder(w http.ResponseWriter, r *http.Request) {
+	updateDisplayOrder(w, r, h.repo.UpdateSpeedLimitDisplayOrder)
+}
+func updateDisplayOrder(w http.ResponseWriter, r *http.Request, save func([]int64, []int64) error) {
+	if r.Method != http.MethodPost {
+		response.WriteJSON(w, response.Err(400, "请求方法错误"))
+		return
+	}
+	var req struct {
+		IDs         []int64 `json:"ids"`
+		ExpectedIDs []int64 `json:"expectedIds"`
+	}
+	if err := decodeJSON(r.Body, &req); err != nil {
+		response.WriteJSON(w, response.Err(400, "请求参数错误"))
+		return
+	}
+	if err := save(req.IDs, req.ExpectedIDs); err != nil {
+		code := 500
+		if errors.Is(err, repo.ErrInvalidDisplayOrder) {
+			code = 400
+		}
+		if errors.Is(err, repo.ErrDisplayOrderConflict) {
+			code = 409
+		}
+		msg := "排序保存失败，请刷新后重试"
+		if code != 500 {
+			msg = err.Error()
+		}
+		response.WriteJSON(w, response.Err(code, msg))
+		return
+	}
+	response.WriteJSON(w, response.OKEmpty())
+}