feat: expose Chatelet over the LNbits nostr transport (#1)

Register kind-21000 RPC handlers on the core nostr_transport dispatcher so
the booking flow runs over relays with no HTTP, mirroring lnurlp:

- operator (AUTH_WALLET): room create/update/publish, block create — all
  ownership-checked; room_list_mine (AUTH_ACCOUNT).
- public (AUTH_NONE): room_list/get (wallet id stripped), availability,
  booking_request, booking_get. Guest identity is the signed sender_pubkey,
  so no guest_pubkey is trusted from the body.
- register_link_owner_resolver(tag=chatelet, key=booking_id) lets the
  operator stream settlements via subscribe_payments.

Handlers delegate to services.py — no logic duplicated. Graceful no-op if
the core transport module isn't in this LNbits build (pre-#4). Guests can't
subscribe to the operator wallet, so they poll booking_get to confirm.

Note documented in event-flow.md: with availability now an RPC, the custom
kind:22000/22001 pair is redundant for RPC clients (revisit in #2).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_019VUQCfdqiLSsFS2jcGnaFD

__init__.py

@@ -35,12 +35,57 @@ def chatelet_start():
     scheduled_tasks.append(
         create_permanent_unique_task("chatelet_hold_expiry", expire_holds_loop)
     )
-    # TODO(relay): once relay plumbing lands, also start the inbound Nostr
-    # subscription so guests can query availability + book over Nostr:
-    #   from .nostr.service import subscribe_inbound
-    #   scheduled_tasks.append(
-    #       create_permanent_unique_task("chatelet_nostr_in", subscribe_inbound)
-    #   )
+
+    # Expose the booking flow over the core LNbits nostr transport (kind-21000
+    # RPC) so an HTTP-allergic client can drive Chatelet over relays. Also wire
+    # the booking-owner resolver so the operator can stream booking
+    # settlements via subscribe_payments({tag:"chatelet", link_id:<booking_id>}).
+    # No-op if the core transport module isn't present in this LNbits build.
+    try:
+        from lnbits.core.services.nostr_transport.dispatcher import (
+            AUTH_ACCOUNT,
+            AUTH_NONE,
+            AUTH_WALLET,
+            register_rpc,
+        )
+        from lnbits.core.services.nostr_transport.subscriptions import (
+            register_link_owner_resolver,
+        )
+    except ImportError:
+        return
+
+    from .transport_rpcs import (
+        handle_availability,
+        handle_block_create,
+        handle_booking_get,
+        handle_booking_request,
+        handle_room_create,
+        handle_room_get,
+        handle_room_list,
+        handle_room_list_mine,
+        handle_room_publish,
+        handle_room_update,
+        resolve_chatelet_owner,
+    )
+
+    # operator (wallet-scoped)
+    register_rpc("chatelet_room_create", handle_room_create, AUTH_WALLET)
+    register_rpc("chatelet_room_update", handle_room_update, AUTH_WALLET)
+    register_rpc("chatelet_room_publish", handle_room_publish, AUTH_WALLET)
+    register_rpc("chatelet_block_create", handle_block_create, AUTH_WALLET)
+    register_rpc("chatelet_room_list_mine", handle_room_list_mine, AUTH_ACCOUNT)
+    # public (discovery + guest booking)
+    register_rpc("chatelet_room_list", handle_room_list, AUTH_NONE)
+    register_rpc("chatelet_room_get", handle_room_get, AUTH_NONE)
+    register_rpc("chatelet_availability", handle_availability, AUTH_NONE)
+    register_rpc("chatelet_booking_request", handle_booking_request, AUTH_NONE)
+    register_rpc("chatelet_booking_get", handle_booking_get, AUTH_NONE)
+
+    # tasks.py stamps extra["booking_id"] on settlement (see on_invoice_paid),
+    # so override the default link_extra_key ("link") to match.
+    register_link_owner_resolver(
+        "chatelet", resolve_chatelet_owner, link_extra_key="booking_id"
+    )
 
 
 __all__ = [