- Create admin-tags.ts with GET list, GET single, POST, PUT (cycle guard → 400), DELETE - Register /tags route in admin.ts - Add 13-test integration suite covering CRUD, cycle detection, orphan behavior
- Create admin-tags.ts with GET list, GET single, POST, PUT (cycle guard → 400), DELETE - Register /tags route in admin.ts - Add 13-test integration suite covering CRUD, cycle detection, orphan behavior