fix(ui): also resync an open game on a foreground regain without a stream drop

Closes the residual tail of the previous commit: when the live stream stays
alive across a brief suspend (Telegram/iOS can pause the socket without tearing
it down), an in-game event shed from a full hub buffer is never recovered by
the reconnect refetch (no reconnect) or the open-game poll (it only runs while
the stream is down). Mirror the lobby's focus re-poll: bump app.resync on a
foreground regain that did not drop the stream, and have Game.svelte refetch
the open game once per resync. Also rescues a missed move/game_over after a
suspend. Add a silent-join mock seam + an e2e isolating this path; extend the
ARCHITECTURE §10 fallback note.

docs/ARCHITECTURE.md

@@ -574,8 +574,9 @@ verbatim. Auto-match needs no match poll — `Enqueue` returns the game the play
 synchronously, and an opponent later taking the open seat arrives as the in-app **opponent-joined**
 event. Unlike a move, that event has no follow-up delta to trigger the move-count gap recovery, so
 the waiting game screen recovers a missed join itself: it **polls `game.state` while the stream is
-down and refetches once on stream reconnect**, so a join missed during an outage or while the app
-was backgrounded still resolves the open game in place. For the lobby **notification badge** (incoming friend requests + open
+down, refetches once on stream reconnect, and resyncs on a foreground regain that did not drop the
+stream** (covering an event shed from a full hub buffer while suspended), so a join missed during an
+outage or while the app was backgrounded still resolves the open game in place. For the lobby **notification badge** (incoming friend requests + open
 invitations) the client re-polls on the `notify` event and on lobby open / focus, covering a push
 missed while the app was hidden. **Out-of-app platform push** is a fallback
 the **gateway** routes from the same firehose: for an event whose recipient has **no