fix(calls): Reject sends the decline to the ring notification (#313)

handleReject related the MSC4310 decline to the caller's call.member event
(the notification's reference), but MSC4310 and Element Call match a
decline against the rtc.notification event itself, so the caller kept
"Calling…" for the full 90 s after being told "Declined", and declines
from other clients (correctly referencing the notification) didn't stop
Lotus ringing on other devices.

- The incoming call keeps the notification's own event id; Reject relates
  the decline to it.
- The "declined on another device" dismissal and declinedRing accept
  either id (older Lotus builds referenced the membership).
- The missed-call line is skipped for a call we declined.

Verified headless (DM, Bob rings, Reject): the decline used to reference
the membership; it now references the notification. Unit test added.

Fixes #313

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/app/utils/callRing.ts

@@ -40,7 +40,18 @@ export const hasActiveCallMembership = (room: Room, userId: string): boolean =>
  * declined it (our own RTCDecline relates to it) — e.g. replayed together with
  * the ring in the first sync after a restart, before any dismiss listener.
  */
-export const declinedRing = (room: Room, refEventId: string, myUserId: string): boolean =>
+export const declinedRing = (
+  room: Room,
+  ringIds: string | Array<string | undefined>,
+  myUserId: string,
+): boolean => {
+  // [Gitea #313] A decline references the notification event (MSC4310); older
+  // Lotus builds referenced the call membership instead. Match either.
+  const ids = new Set((Array.isArray(ringIds) ? ringIds : [ringIds]).filter(Boolean));
+  return declinedAny(room, ids, myUserId);
+};
+
+const declinedAny = (room: Room, ids: Set<string | undefined>, myUserId: string): boolean =>
   room
     .getLiveTimeline()
     .getEvents()
@@ -48,5 +59,5 @@ export const declinedRing = (room: Room, refEventId: string, myUserId: string):
       (ev) =>
         ev.getType() === 'org.matrix.msc4310.rtc.decline' &&
         ev.getSender() === myUserId &&
-        ev.getRelation()?.event_id === refEventId,
+        ids.has(ev.getRelation()?.event_id),
     );