fix(calls): no "Missed call" in voice rooms or space channels

Joining a voice channel alone sends a call notification (m.rtc.notification)
to the room, and the timeline rendered every unanswered one as "Missed call
from X", so everyone in the channel saw a missed call from someone who had
just joined it. Ringing already excluded these rooms; the missed-call line
didn't.

utils/callRing.ts (unit-tested) holds the one rule for both: only DMs and
invite-only groups outside any space ring or show "Missed call"; voice
rooms, space channels, restricted and public rooms don't.

Verified headless with the same two notifications from Bob: the Voice
Lounge chat showed 2 "Missed call" lines before, 0 after; a small
invite-only group still shows its missed call.

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

src/app/utils/callRing.ts

@@ -0,0 +1,18 @@
+import { JoinRule, Room } from 'matrix-js-sdk';
+import { StateEvent } from '../../types/matrix/room';
+import { getStateEvents } from './room';
+
+/**
+ * Whether a call notification in this room may ring — and, by the same rule,
+ * whether an unanswered one may show as "Missed call" (Gitea #162 follow-up).
+ * Only DMs and invite-only groups outside any space ring, i.e. rooms where the
+ * call button is shown. Persistent voice rooms, space channels, restricted and
+ * public rooms never do: joining a voice channel alone is normal and isn't a
+ * "call" anyone missed.
+ */
+export const isRingableRoom = (room: Room, isDirect: boolean): boolean => {
+  if (room.isCallRoom()) return false;
+  if (isDirect) return true;
+  const isSpaceChild = getStateEvents(room, StateEvent.SpaceParent).length > 0;
+  return !isSpaceChild && room.getJoinRule() === JoinRule.Invite;
+};