🔎 feat(topup): add order number search for billing history (admin and user)

Enable searching topup records by trade_no across both admin-wide and user-only views.

Frontend
- TopupHistoryModal.jsx:
  - Add search input with prefix icon (IconSearch) to filter by order number
  - Send `keyword` query param to backend; works with both endpoints:
    - Admin: GET /api/user/topup?p=1&page_size=10&keyword=...
    - User:  GET /api/user/topup/self?p=1&page_size=10&keyword=...
  - Keep endpoint auto-switching based on role (isAdmin)
  - Minor UI polish: outlined admin action button; keep Coins icon for amount

Backend
- model/topup.go:
  - Add SearchUserTopUps(userId, keyword, pageInfo)
  - Add SearchAllTopUps(keyword, pageInfo)
  - Both support pagination and `trade_no LIKE %keyword%` filtering (ordered by id desc)
- controller/topup.go:
  - GetUserTopUps / GetAllTopUps accept optional `keyword` and route to search functions when present

Routes
- No new endpoints; search is enabled via `keyword` on existing:
  - GET /api/user/topup
  - GET /api/user/topup/self

Affected files
- model/topup.go
- controller/topup.go
- web/src/components/topup/modals/TopupHistoryModal.jsx

controller/topup.go

@@ -318,8 +318,18 @@ func RequestAmount(c *gin.Context) {
 func GetUserTopUps(c *gin.Context) {
 	userId := c.GetInt("id")
 	pageInfo := common.GetPageQuery(c)
+	keyword := c.Query("keyword")
 
-	topups, total, err := model.GetUserTopUps(userId, pageInfo)
+	var (
+		topups []*model.TopUp
+		total  int64
+		err    error
+	)
+	if keyword != "" {
+		topups, total, err = model.SearchUserTopUps(userId, keyword, pageInfo)
+	} else {
+		topups, total, err = model.GetUserTopUps(userId, pageInfo)
+	}
 	if err != nil {
 		common.ApiError(c, err)
 		return
@@ -333,8 +343,18 @@ func GetUserTopUps(c *gin.Context) {
 // GetAllTopUps 管理员获取全平台充值记录
 func GetAllTopUps(c *gin.Context) {
 	pageInfo := common.GetPageQuery(c)
+	keyword := c.Query("keyword")
 
-	topups, total, err := model.GetAllTopUps(pageInfo)
+	var (
+		topups []*model.TopUp
+		total  int64
+		err    error
+	)
+	if keyword != "" {
+		topups, total, err = model.SearchAllTopUps(keyword, pageInfo)
+	} else {
+		topups, total, err = model.GetAllTopUps(pageInfo)
+	}
 	if err != nil {
 		common.ApiError(c, err)
 		return