feat(brand): add brand sort order and drag-to-reorder

Add a sort_order column to brands with a migration, expose a
PUT /api/tenant/brands/order reorder endpoint, and wire the
admin-web BrandsView with drag-and-drop reordering plus i18n.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

server/internal/tenant/transport/brand_handler.go

@@ -50,6 +50,20 @@ func (h *BrandHandler) Create(c *gin.Context) {
 	response.SuccessWithStatus(c, 201, data)
 }
 
+func (h *BrandHandler) Reorder(c *gin.Context) {
+	var req app.BrandReorderRequest
+	if err := c.ShouldBindJSON(&req); err != nil {
+		response.Error(c, response.ErrBadRequest(40001, "invalid_params", err.Error()))
+		return
+	}
+	data, err := h.svc.Reorder(c.Request.Context(), req)
+	if err != nil {
+		response.Error(c, err)
+		return
+	}
+	response.Success(c, data)
+}
+
 func (h *BrandHandler) Detail(c *gin.Context) {
 	id, err := strconv.ParseInt(c.Param("id"), 10, 64)
 	if err != nil {