🔎 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

model/topup.go

@@ -165,6 +165,74 @@ func GetAllTopUps(pageInfo *common.PageInfo) (topups []*TopUp, total int64, err
 	return topups, total, nil
 }
 
+// SearchUserTopUps 按订单号搜索某用户的充值记录
+func SearchUserTopUps(userId int, keyword string, pageInfo *common.PageInfo) (topups []*TopUp, total int64, err error) {
+	tx := DB.Begin()
+	if tx.Error != nil {
+		return nil, 0, tx.Error
+	}
+	defer func() {
+		if r := recover(); r != nil {
+			tx.Rollback()
+		}
+	}()
+
+	query := tx.Model(&TopUp{}).Where("user_id = ?", userId)
+	if keyword != "" {
+		like := "%%" + keyword + "%%"
+		query = query.Where("trade_no LIKE ?", like)
+	}
+
+	if err = query.Count(&total).Error; err != nil {
+		tx.Rollback()
+		return nil, 0, err
+	}
+
+	if err = query.Order("id desc").Limit(pageInfo.GetPageSize()).Offset(pageInfo.GetStartIdx()).Find(&topups).Error; err != nil {
+		tx.Rollback()
+		return nil, 0, err
+	}
+
+	if err = tx.Commit().Error; err != nil {
+		return nil, 0, err
+	}
+	return topups, total, nil
+}
+
+// SearchAllTopUps 按订单号搜索全平台充值记录（管理员使用）
+func SearchAllTopUps(keyword string, pageInfo *common.PageInfo) (topups []*TopUp, total int64, err error) {
+	tx := DB.Begin()
+	if tx.Error != nil {
+		return nil, 0, tx.Error
+	}
+	defer func() {
+		if r := recover(); r != nil {
+			tx.Rollback()
+		}
+	}()
+
+	query := tx.Model(&TopUp{})
+	if keyword != "" {
+		like := "%%" + keyword + "%%"
+		query = query.Where("trade_no LIKE ?", like)
+	}
+
+	if err = query.Count(&total).Error; err != nil {
+		tx.Rollback()
+		return nil, 0, err
+	}
+
+	if err = query.Order("id desc").Limit(pageInfo.GetPageSize()).Offset(pageInfo.GetStartIdx()).Find(&topups).Error; err != nil {
+		tx.Rollback()
+		return nil, 0, err
+	}
+
+	if err = tx.Commit().Error; err != nil {
+		return nil, 0, err
+	}
+	return topups, total, nil
+}
+
 // ManualCompleteTopUp 管理员手动完成订单并给用户充值
 func ManualCompleteTopUp(tradeNo string) error {
 	if tradeNo == "" {