feat(api): keyless GET /api/v1/public/bookings/{id} for guests

The guest cannot subscribe to the operator's wallet and the existing
booking read needs a wallet invoice key, so a client had no way to wait
for awaiting_payment -> confirmed over HTTP short of polling the invoice
on LNbits core. Add the HTTP twin of the RPC door's chatelet_booking_get:
the 10-char booking id from the quote is the capability, and the response
is public_booking_dict — lifecycle, dates and money only, with the guest's
pubkey/contact and the Lightning/Nostr plumbing stripped.

Closes #18

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

views_api.py

@@ -24,6 +24,7 @@ from .models import (
     CreateRoomData,
     Room,
     RoomStatus,
+    public_booking_dict,
     public_room_dict,
 )
 from .nostr import service as nostr
@@ -243,3 +244,15 @@ async def api_get_booking(
     if not booking:
         raise HTTPException(404, "Booking not found")
     return booking
+
+
+@chatelet_api_router.get("/api/v1/public/bookings/{booking_id}")
+async def api_public_booking(booking_id: str) -> dict:
+    """Guest read-back of their own booking (keyless). The guest can't
+    subscribe to the operator's wallet, so this is how a client waits for
+    `awaiting_payment` -> `confirmed` (or sees `expired` / `declined`)
+    without a key — the HTTP twin of the RPC door's chatelet_booking_get."""
+    booking = await crud.get_booking(booking_id)
+    if not booking:
+        raise HTTPException(404, "Booking not found")
+    return public_booking_dict(booking)