feat: events_ticket_register RPC over nostr transport

Organizer-side ticket scanning over LNbits's freshly-merged
nostr-transport (kind 21000, NIP-44 v2). The organizer signs the
RPC event with their Nostr key; the transport dispatcher resolves
pubkey → Account → wallet (AUTH_WALLET) and the handler verifies
event-level ownership (event.wallet ∈ caller_user.wallet_ids)
before flipping `registered = True`.

Idempotence + state transitions mirror the legacy HTTP endpoint:
"Ticket not paid for" / "Ticket already registered" / "Ticket
does not exist on this event" / "You do not own this event" come
back as ERROR responses. Registration in events_start() is
guarded with try/except ImportError so the extension still loads
on older LNbits versions that pre-date the transport (HTTP path
stays the fallback there).

Webapp uses this as the new primary scan call site instead of
the legacy HTTP endpoint — see companion webapp PR.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

__init__.py

@@ -46,6 +46,27 @@ def events_start():
     task1 = create_permanent_unique_task("ext_events", wait_for_paid_invoices)
     scheduled_tasks.append(task1)
 
+    # Register nostr-transport RPCs. Swallow ImportError on older LNbits
+    # versions that pre-date the transport (the events extension still
+    # works fine via HTTP without it).
+    try:
+        from lnbits.core.services.nostr_transport.dispatcher import (
+            AUTH_WALLET,
+            register_rpc,
+        )
+
+        from .transport_rpcs import handle_events_ticket_register
+
+        register_rpc(
+            "events_ticket_register", handle_events_ticket_register, AUTH_WALLET
+        )
+        logger.info("[EVENTS] Registered nostr-transport RPC: events_ticket_register")
+    except ImportError:
+        logger.info(
+            "[EVENTS] nostr_transport not available on this LNbits — "
+            "ticket scanner over Nostr disabled, HTTP endpoint still works"
+        )
+
     async def _start_nostr_client():
         global nostr_client
         await asyncio.sleep(10)  # Wait for nostrclient to be ready