fix(calls): a finished call no longer rings again after a reload (#312)

After a reload/restart within a ring's lifetime, the catch-up sync replays
the ring together with the caller's hang-up and our own decline, and the
MatrixRTC session can keep the stale join. The client rang again for up to
90 s and showed "1 Live" (call screen instead of chat) for minutes.

- Before ringing, check the room STATE (utils/callRing.ts, unit-tested):
  no ring if we already declined that ring or are in the call; if the
  caller has no active membership yet, re-check after 4 s (a real call's
  membership can land just after its ring) and ring only if they joined.
- The "caller gone" dismissal also consults room state, not only the
  possibly stale session.
- When sync becomes live (startup or reconnect), recompute every active
  RTC session from the current state, clearing a stale "Live".

Verified headless (Bob's membership + ring in an invite-only room):
live ring rings; hang-up stops it; reload within the window: before
rang again + "1 Live", now no ring and no "Live"; a ring that arrives
just before the membership still rings.

Fixes #312

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

src/app/utils/callRing.ts

@@ -16,3 +16,37 @@ export const isRingableRoom = (room: Room, isDirect: boolean): boolean => {
   const isSpaceChild = getStateEvents(room, StateEvent.SpaceParent).length > 0;
   return !isSpaceChild && room.getJoinRule() === JoinRule.Invite;
 };
+
+/** A call-membership state event that is still "in the call" (left = empty content). */
+const isActiveMembership = (content: Record<string, unknown> | undefined): boolean =>
+  !!content &&
+  (typeof content.application === 'string' ||
+    (Array.isArray(content.memberships) && content.memberships.length > 0));
+
+/**
+ * [Gitea #312] Whether `userId` is in a call in `room` according to the room's
+ * current STATE. After a reload the MatrixRTC session can be stale (a join and
+ * leave replayed in one catch-up batch), but the state is right.
+ */
+export const hasActiveCallMembership = (room: Room, userId: string): boolean =>
+  getStateEvents(room, StateEvent.GroupCallMemberPrefix).some(
+    (ev) =>
+      (ev.getSender() === userId || ev.getStateKey()?.includes(userId)) &&
+      isActiveMembership(ev.getContent()),
+  );
+
+/**
+ * [Gitea #312] Whether we already handled the ring `refEventId` points at:
+ * 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 =>
+  room
+    .getLiveTimeline()
+    .getEvents()
+    .some(
+      (ev) =>
+        ev.getType() === 'org.matrix.msc4310.rtc.decline' &&
+        ev.getSender() === myUserId &&
+        ev.getRelation()?.event_id === refEventId,
+    );