feat: GET /tickets/event/{event_id}/stats for door-scanner roster

Mirrors the events_list_event_tickets nostr-transport RPC for callers
that don't hold a raw user prvkey (the webapp post-#9, in particular —
useTicketScanner.refreshStats now has a working HTTP path). Auth:
wallet admin_key + the event's wallet must be in the caller's wallet
set, matching the register endpoint's owner check.

Without this endpoint the activities scanner page loaded its initial
counts (via no-op fallbacks) but every post-scan refreshStats returned
404, leaving the Scanned counter stuck at 0 even though registrations
landed correctly. Surfaced by aio-demo manual test on 2026-06-03.

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

views_api.py

@@ -47,6 +47,7 @@ from .crud import (
     get_settings,
     get_ticket,
     get_tickets,
+    get_tickets_by_event,
     get_tickets_by_payment_hash,
     get_tickets_by_user_id,
     purge_unpaid_tickets,
@@ -832,3 +833,52 @@ async def api_event_register_ticket(
     ticket.reg_timestamp = datetime.now(timezone.utc)
     ticket = await update_ticket(ticket)
     return ticket
+
+
+@tickets_api_router.get("/event/{event_id}/stats")
+async def api_event_ticket_stats(
+    event_id: str,
+    key_info: WalletTypeInfo = Depends(require_admin_key),
+) -> dict:
+    """Door-scanner roster + counts for one event, organizer-only.
+
+    Mirrors the `events_list_event_tickets` nostr-transport RPC for
+    callers that don't hold a raw user prvkey (the webapp post-#9, in
+    particular). Auth: wallet admin_key + the event's wallet must be
+    in the caller's wallet set.
+    """
+    event = await get_event(event_id)
+    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.",
+        )
+
+    tickets = await get_tickets_by_event(event_id)
+    paid_tickets = [t for t in tickets if t.paid]
+    registered_count = sum(1 for t in paid_tickets if t.registered)
+
+    return {
+        "event_id": event_id,
+        "sold": len(paid_tickets),
+        "registered": registered_count,
+        "remaining": len(paid_tickets) - registered_count,
+        "tickets": [
+            {
+                "id": t.id,
+                "name": t.name,
+                "registered": t.registered,
+                "registered_at": (
+                    t.reg_timestamp.isoformat() if t.reg_timestamp else None
+                ),
+            }
+            for t in paid_tickets
+        ],
+    }