release: v1.9.0 — command sequencing, episode-aware sync, echo suppression

- Add per-peer monotonically increasing seq numbers (localSeq + lastSeqBySender)
- Server relays seq for stale command detection (backward compatible)
- Replace expectedEvents (1500ms timeout) with _suppressTimers (per-type, 300ms)
- Fix FORCE_SYNC_ACK missing seq (stale-ACK guard)
- Fix episode lobby readyPeers asymmetry (initiator now included)
- Add extractEpisodeId() parsing S01E01, Season 1 Ep 1, Folge 5, Ep. 3, #42
- Add isDifferentEpisode() guard blocking cross-episode sync commands
- Add sameEpisode() for format-tolerant lobby title matching
- Guard controlled via autoSyncNextEpisode setting
- Reduce reactive lock 1000ms → 300ms
- Fix routeToContent unbounded retry (max 3 attempts)
- Fix server bcrypt.hash failure crashing join flow
- Fix sameEpisode(null, title) returning true
- Fix forceSyncTimeout leak on rapid force sync clicks
- Persist lastSeqBySender across service worker restarts
- Bump version: 1.8.10 → 1.9.0

server/index.js

@@ -342,6 +342,11 @@ io.on('connection', (socket) => {
                 }
             }
 
+            if (!room) {
+                socket.emit(EVENTS.ERROR, { message: "Join error" });
+                return;
+            }
+
             if (!createdByMe) {
                 if (room.passwordHash) {
                     if (!password || !(await bcrypt.compare(password, room.passwordHash))) {