fix(presence): leaving Do Not Disturb restores your status instead of "dnd" (#283)

Lotus encodes DND as status_msg "dnd". After switching back to Auto, the
heartbeat read the server's status, adopted "dnd" as the user's own and
kept re-sending it, so the custom status was lost and other clients kept
showing "dnd"; the Settings status field showed "dnd" too.

pickHeartbeatStatus (unit-tested) never adopts the "dnd" sentinel and
falls back to the device's real status; Profile neither mirrors it into
the local status nor shows it in the field.

Verified on the local Synapse: "🎮 Gaming" → DND (unavailable/dnd) → Auto
→ online/"🎮 Gaming" (before: online/"dnd").

Still open in #283: while in DND other clients show the literal "dnd";
that needs MSC3026 busy presence on the homeserver (matrix#19).

Refs #283

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

src/app/utils/ownStatusSync.ts

@@ -9,6 +9,9 @@
  * overridden by a server read that hasn't caught up yet.
  */
 
+/** The status_msg Lotus sends for Do Not Disturb (see usePresenceUpdater). */
+export const DND_STATUS_SENTINEL = 'dnd';
+
 /** Trust this device's own copy for this long after it saved or cleared it. */
 export const LOCAL_WRITE_GRACE_MS = 15_000;
 
@@ -37,7 +40,12 @@ export const pickHeartbeatStatus = ({
   lastLocalWriteAt: number;
   now: number;
 }): string => {
-  if (!server || server.presence === 'offline') return local;
-  if (now - writtenAt < LOCAL_WRITE_GRACE_MS) return local;
+  // [Gitea #283] Lotus encodes Do Not Disturb as status_msg "dnd", so a device
+  // leaving DND must not adopt that sentinel as the user's status — keep (and
+  // so restore) the real one it holds locally.
+  const mine = local === DND_STATUS_SENTINEL ? '' : local;
+  if (!server || server.presence === 'offline') return mine;
+  if (now - writtenAt < LOCAL_WRITE_GRACE_MS) return mine;
+  if (server.status_msg === DND_STATUS_SENTINEL) return mine;
   return server.status_msg ?? '';
 };