fix: require admin_key + owner check on PUT /tickets/register

The legacy register endpoint had no auth decorator and no
event-ownership check — any caller who knew a ticket id could
mark it registered. Add require_admin_key (matches the rest of
the wallet-bound endpoints in this file) and verify the caller's
user owns the event the ticket belongs to.

Breaking change for any external integration that hit this
endpoint unauthed; the in-tree Quasar register page
(static/js/register.js) already sends the session admin_key via
LNbits.api.request so it keeps working.

The Nostr-transport flow at events_ticket_register (previous
commit) is the preferred call site for new callers; this HTTP
path stays for the legacy LNbits admin UI.

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

views_api.py

@@ -766,7 +766,24 @@ async def api_ticket_resend_email(
 
 
 @tickets_api_router.put("/register/{ticket_id}")
-async def api_event_register_ticket(ticket_id) -> Ticket:
+async def api_event_register_ticket(
+    ticket_id: str,
+    key_info: WalletTypeInfo = Depends(require_admin_key),
+) -> Ticket:
+    """Mark a ticket as registered at the door.
+
+    Auth: wallet admin_key. Caller must own the event the ticket
+    belongs to — we check `event.wallet` against the user's full
+    wallet set so an organizer with multiple wallets can scan
+    regardless of which wallet's key they're using.
+
+    Until v1.6.1-aio.3 this endpoint had no auth, which meant any
+    caller who knew a ticket id could register it. The
+    Nostr-transport flow at `events_ticket_register` is now the
+    preferred call site for the webapp; this HTTP path stays for
+    the legacy LNbits Quasar register page which already sends
+    the wallet admin_key through `LNbits.api.request`.
+    """
     ticket = await get_ticket(ticket_id)
 
     if not ticket:
@@ -774,6 +791,20 @@ async def api_event_register_ticket(ticket_id) -> Ticket:
             status_code=HTTPStatus.NOT_FOUND, detail="Ticket does not exist."
         )
 
+    event = await get_event(ticket.event)
+    if not event:
+        raise HTTPException(
+            status_code=HTTPStatus.NOT_FOUND, detail="Event does not exist."
+        )
+
+    user = await get_user(key_info.wallet.user)
+    owned_wallet_ids = user.wallet_ids if user else [key_info.wallet.id]
+    if event.wallet not in owned_wallet_ids:
+        raise HTTPException(
+            status_code=HTTPStatus.FORBIDDEN,
+            detail="You do not own this event.",
+        )
+
     if not ticket.paid:
         raise HTTPException(
             status_code=HTTPStatus.FORBIDDEN, detail="Ticket not paid for."