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/migrations/20260708110000_add_brand_sort_order.down.sql

@@ -0,0 +1,4 @@
+DROP INDEX IF EXISTS idx_brands_tenant_sort_active;
+
+ALTER TABLE brands
+DROP COLUMN IF EXISTS sort_order;

server/migrations/20260708110000_add_brand_sort_order.up.sql

@@ -0,0 +1,24 @@
+ALTER TABLE brands
+ADD COLUMN sort_order INT;
+
+WITH ordered_brands AS (
+    SELECT
+        id,
+        ROW_NUMBER() OVER (
+            PARTITION BY tenant_id
+            ORDER BY created_at DESC, id DESC
+        )::INT * 1000 AS next_sort_order
+    FROM brands
+)
+UPDATE brands
+SET sort_order = ordered_brands.next_sort_order
+FROM ordered_brands
+WHERE brands.id = ordered_brands.id;
+
+ALTER TABLE brands
+ALTER COLUMN sort_order SET DEFAULT 1000,
+ALTER COLUMN sort_order SET NOT NULL;
+
+CREATE INDEX idx_brands_tenant_sort_active
+    ON brands(tenant_id, sort_order ASC, created_at DESC, id DESC)
+    WHERE deleted_at IS NULL;