feat: honest AI opponent in quick game

New Game's quick game gains an explicit opponent selector — 🤖 AI (default)
or 👤 Random player. AI starts a game seated with a pooled robot that joins
and moves at once: no per-move timeout (a 7-day inactivity loss reusing the
turn-timeout sweeper), chat/nudge disabled, no statistics, the opponent shown
as 🤖 everywhere. The random path (disguised robot) is unchanged.

Driven by one game flag (games.vs_ai), set only on AI-started games so the
disguised path is never revealed; Matchmaker.StartVsAI seats the robot
directly (no open pool); the robot replies event-driven via the game service's
after-commit/after-create hook. Wire: vs_ai on EnqueueRequest + GameView.

ui/src/lib/i18n/ru.ts

@@ -45,7 +45,6 @@ export const ru: Record<MessageKey, string> = {
   'lobby.vs': 'против {opponents}',
 
   'new.title': 'Новая игра',
-  'new.subtitle': 'Автоподбор соперника',
   'new.english': 'Scrabble',
   'new.russian': 'Скрэббл',
   'new.erudit': 'Эрудит',
@@ -266,6 +265,9 @@ export const ru: Record<MessageKey, string> = {
   'new.start': 'Начать игру',
   'new.invited': 'Приглашение отправлено.',
   'new.noFriends': 'Сначала добавьте друзей, чтобы пригласить их.',
+  'new.opponentAI': 'ИИ',
+  'new.opponentRandom': 'Случайный игрок',
+  'new.aiInactiveLimit': 'Поражение, если 7 дней нет активности',
 
   'stats.title': 'Статистика',
   'stats.wins': 'Победы',