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/game/Chat.svelte

@@ -12,6 +12,7 @@
     canNudge = false,
     waiting = false,
     nudgeOnCooldown = false,
+    vsAi = false,
     onsend,
     onnudge,
   }: {
@@ -34,6 +35,9 @@
     // are disabled (there is no one to message or hurry yet).
     waiting?: boolean;
     nudgeOnCooldown?: boolean;
+    // vsAi disables both controls in an honest-AI game: the opponent is a robot, so there is
+    // nobody to message or hurry. The fields still show (turn-driven), but disabled.
+    vsAi?: boolean;
     onsend: (text: string) => void;
     onnudge: () => void;
   } = $props();
@@ -67,9 +71,10 @@
         maxlength="60"
         placeholder={t('chat.placeholder')}
         bind:value={text}
-        onkeydown={(e) => e.key === 'Enter' && !busy && send()}
+        disabled={vsAi}
+        onkeydown={(e) => e.key === 'Enter' && !busy && !vsAi && send()}
       />
-      <button class="iconbtn" onclick={send} disabled={busy || waiting || !connection.online} aria-label={t('chat.send')}>⬆️</button>
+      <button class="iconbtn" onclick={send} disabled={busy || waiting || vsAi || !connection.online} aria-label={t('chat.send')}>⬆️</button>
     {:else if myTurn}
       <!-- Own turn, the one allowed message already sent: a caption holds the row until the
            next turn (no nudge — there is no one to hurry on your own turn). -->
@@ -77,7 +82,7 @@
     {:else if canNudge}
       <!-- A flex:1 caption keeps the nudge pinned right whether or not the cooldown text shows. -->
       <span class="cooldown">{nudgeOnCooldown ? t('chat.awaitingReply') : ''}</span>
-      <button class="iconbtn" onclick={onnudge} disabled={busy || waiting || nudgeOnCooldown || !connection.online} aria-label={t('chat.nudgeAction')}>🛎️</button>
+      <button class="iconbtn" onclick={onnudge} disabled={busy || waiting || nudgeOnCooldown || vsAi || !connection.online} aria-label={t('chat.nudgeAction')}>🛎️</button>
     {/if}
   </div>
 </div>

ui/src/game/ChatScreen.svelte

@@ -113,4 +113,16 @@
   }
 </script>
 
-<Chat {messages} {myId} {busy} myTurn={isMyTurn} {canSend} {canNudge} {waiting} {nudgeOnCooldown} onsend={sendChat} onnudge={nudge} />
+<Chat
+  {messages}
+  {myId}
+  {busy}
+  myTurn={isMyTurn}
+  {canSend}
+  {canNudge}
+  {waiting}
+  {nudgeOnCooldown}
+  vsAi={!!view && view.game.vsAi}
+  onsend={sendChat}
+  onnudge={nudge}
+/>

ui/src/game/Game.svelte

@@ -869,6 +869,8 @@
   function seatName(s: { accountId: string; displayName: string } | undefined): string {
     if (!s) return '';
     if (s.accountId === app.session?.userId) return t('common.you');
+    // An honest-AI game shows the robot opponent as 🤖, never its (pooled human-like) name.
+    if (view?.game.vsAi) return '🤖';
     if (!s.accountId) return t('game.searchingForOpponent');
     return s.displayName;
   }
@@ -876,6 +878,7 @@
   // turnLabel is the under-board status when it is not the viewer's turn: the opponent's name
   // once they have joined, or a generic "opponent's turn" while the seat is still empty (waiting).
   function turnLabel(): string {
+    if (view?.game.vsAi) return '🤖';
     const s = view?.game.seats[view?.game.toMove ?? -1];
     if (s && s.accountId && s.accountId !== app.session?.userId) return s.displayName;
     return t('game.opponentsTurn');
@@ -885,6 +888,8 @@
   // (not the still-empty seat of an open game) who is not yet a friend (an already-requested
   // opponent still shows it, but disabled).
   function canAddFriend(accountId: string): boolean {
+    // Never offer add-friend against an AI opponent.
+    if (view?.game.vsAi) return false;
     return !!accountId && !app.profile?.isGuest && accountId !== app.session?.userId && !friends.has(accountId);
   }
 </script>