feat(http): CMS pages + REST API for owners and customers

views.py (Jinja CMS pages, /restaurant/...):
  - /                   restaurant list / dashboard
  - /{slug}             menu builder
  - /{slug}/orders      order monitor
  - /{slug}/kds         kitchen display
  - /{slug}/settings    restaurant + Nostr settings

views_api.py (REST under /restaurant/api/v1/):

  Owner write-side (require_admin_key, ownership-checked):
    - restaurants CRUD (publishes kind 0 metadata to Nostr on
      create/update; signs with restaurant.nostr_pubkey override
      or LNbits Account fallback)
    - categories + subcategories CRUD
    - menu_items CRUD (publishes/replaces kind 30402 NIP-99
      listings on create/update; sends kind 5 NIP-09 deletion on
      delete)
    - modifier_groups + modifiers CRUD
    - availability_windows CRUD
    - orders status transitions (PUT /api/v1/orders/{id}/status/{new})
    - print_jobs/{id}/ack
    - settings (admin-only)

  Customer-facing (no auth, customer pubkey optional):
    - GET /api/v1/restaurants/{id}                profile
    - GET /api/v1/restaurants/{id}/menu           full menu tree
                                                  (categories +
                                                  subcategories +
                                                  items + modifiers +
                                                  availability) in
                                                  one round trip
    - POST /api/v1/orders/quote                   pre-flight balance
                                                  check; webapp calls
                                                  this *before* opening
                                                  any per-restaurant
                                                  invoice
    - POST /api/v1/orders                         place an order on
                                                  one restaurant,
                                                  returns bolt11

  KDS / order monitor (require_invoice_key, ownership-checked):
    - GET /api/v1/restaurants/{id}/orders
    - GET /api/v1/restaurants/{id}/print_jobs

crud.py: added get_print_job(job_id) helper used by the ack endpoint.

crud.py

@@ -563,6 +563,14 @@ async def update_print_job(job: PrintJob) -> PrintJob:
     return job
 
 
+async def get_print_job(job_id: str) -> Optional[PrintJob]:
+    return await db.fetchone(
+        "SELECT * FROM restaurant.print_jobs WHERE id = :id",
+        {"id": job_id},
+        PrintJob,
+    )
+
+
 async def get_print_jobs(
     restaurant_id: str, status: Optional[str] = None
 ) -> list[PrintJob]: