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/repository/generated/models.go

@@ -122,6 +122,7 @@ type Brand struct {
 	UpdatedAt   pgtype.Timestamptz `json:"updated_at"`
 	DeletedAt   pgtype.Timestamptz `json:"deleted_at"`
 	Website     pgtype.Text        `json:"website"`
+	SortOrder   int32              `json:"sort_order"`
 }
 
 type BrandAssetCleanupEvent struct {