feat(calls): rejoin the voice room after a crash, update or reload (#118)

While joined, a device-local record {roomId, deviceId, joinedAt,
lastSeen, mic, video} is written and refreshed every 30 s; a deliberate
hangup (HangupCall/Close) and logout clear it. On the next start, once
the first sync is in and the room's MatrixRTC session has reported its
members (waited for up to 10 s — it fills a moment after sync), a fresh
record (< 10 min) for this device with someone still in the call yields
either a sticky "Rejoin voice?" toast (tap to rejoin) or an automatic
rejoin, per the new Settings → Calls → After a Restart (Ask / Rejoin
automatically / Do nothing; default Ask). Skipped when our own membership
is already live from another device, or only our stale one is left.
Mic/camera state comes from the record (camera still gated by
cameraOnJoin); PTT is applied by startCall as usual.

Pure decision in utils/callRejoin.ts with tests. Verified headless:
reload mid-call → toast → tap → back in the call; hangup → reload → no
toast; auto mode → back in without a prompt.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01PPmy3tPq869XDW4njjVaKA

src/app/components/CallEmbedProvider.tsx

@@ -48,6 +48,7 @@ import { useCallMembersChange, useCallSession } from '../hooks/useCall';
 import { useCallJoinLeaveSounds } from '../hooks/useCallJoinLeaveSounds';
 import { useCallPolicyRevokedToast } from '../hooks/useCallPolicyRevokedToast';
 import { useCallEndedToast } from '../hooks/useCallEndedToast';
+import { useCallRejoin } from '../hooks/useCallRejoin';
 import { useCallAnnouncements } from '../hooks/useCallAnnouncements';
 import { useMutedTalkWarning } from '../hooks/useMutedTalkWarning';
 import { callAnnouncementAtom } from '../state/callAnnouncement';
@@ -842,6 +843,12 @@ function PipMuteOverlay({ callEmbed }: { callEmbed: CallEmbed }) {
 type CallEmbedProviderProps = {
   children?: ReactNode;
 };
+/** [Gitea #118] Heartbeat + rejoin after a crash/restart; needs the embed container mounted. */
+function CallRejoin({ callEmbed, joined }: { callEmbed?: CallEmbed; joined: boolean }) {
+  useCallRejoin(callEmbed, joined);
+  return null;
+}
+
 export function CallEmbedProvider({ children }: CallEmbedProviderProps) {
   const callEmbed = useAtomValue(callEmbedAtom);
   const callEmbedRef = useRef<HTMLDivElement>(null) as React.RefObject<HTMLDivElement>;
@@ -1294,6 +1301,7 @@ export function CallEmbedProvider({ children }: CallEmbedProviderProps) {
       <CallAnnouncementRegion />
       <CallEmbedRefContextProvider value={callEmbedRef}>
         <IncomingCallListener callEmbed={callEmbed} joined={joined} />
+        <CallRejoin callEmbed={callEmbed} joined={joined} />
         {children}
       </CallEmbedRefContextProvider>
       <div