feat(lobby): enter the game immediately and wait for the opponent inside it

Quick auto-match no longer waits on a separate screen: Enqueue opens a real game seating the caller with an empty opponent seat (new game status 'open') and the player enters it at once. A second human searching the same variant+rule joins that open game; otherwise a background reaper seats a robot after a 90s + random 0-90s wait, pushing a new in-app opponent_joined event that fills the opponent card and re-enables resign and chat in place.

Matchmaking state is now the open games in the database (the in-memory pool, lobby.poll and lobby.cancel are gone), serialised by a per-bucket advisory lock. While a game is open the starter may move on their turn, but resign, chat and nudge are refused; the lobby and opponent card show "searching for opponent".

Schema edited in the baseline (no prod data): 'open' status, nullable game_players.account_id for the empty seat, and a games.open_deadline_at stamp; jet code regenerated.

ui/src/lib/i18n/ru.ts

@@ -52,11 +52,14 @@ export const ru: Record<MessageKey, string> = {
   'new.rulesRussian': '104 фишки · ё — отдельная буква · бинго +50',
   'new.rulesErudit': '131 фишка · ё = е · центр не удваивает · бонус +15',
   'new.moveLimit': 'Время на ход: {n} ч. 00 мин.',
+  'new.searchHint':
+    'Иногда поиск соперника может занимать некоторое время. Если не хотите ждать, после начала игры закройте приложение и возвращайтесь через пару минут.',
 
   'game.bag': '{n} в мешке',
   'game.bagEmpty': 'Мешок пуст',
   'game.hints': 'Подсказки {n}',
   'game.yourTurn': 'Ваш ход',
+  'game.searchingForOpponent': 'Поиск соперника...',
   'game.waiting': 'Ожидаем {name}',
   'game.makeMove': 'Сделать ход',
   'game.reset': 'Сброс',