feat(services): pick a global category from the service page

The service page could not say which category a service belongs to, so the
containment edges defined in settings had nothing to match against.

A Categories tab now selects one — and only selects. Creating, renaming and
deleting stay in Settings > Categories: if every page could create one,
"whole body" would exist three times with three spellings and the
includes edge would stop catching anything.

PATCH /api/v1/service-item/{uuid} carries the choice as
catalog_category_uuid. Absent field leaves the current category alone, null
clears it, and a category from another environment is refused with 422 —
the uuid arrives in the request body where TenantFilter does not reach.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

assets/admin/types/index.ts

@@ -719,6 +719,8 @@ export interface ServiceItem {
     /** نوع خدمت (سرپایی/بستری) — درصد پوشش بیمه بر همین اساس انتخاب می‌شود. */
     service_category?: string;
     service_category_label?: string;
+    /** دستهٔ کاتالوگ سراسری — با `service_category` (enum بیمه‌ای) اشتباه نشود. */
+    catalog_category_uuid?: string | null;
     duration_minutes?: number | null;
     bookable?: boolean;
 }