Add CPU opponents and a table type selector (cash only / friends / CPU)

- Create screen: choose キャッシュオンリー (real cards, chips only), 友人戦
  (server deals and settles) or CPU戦 (友人戦 plus 1–8 CPU players); replaces
  the card toggle. The lobby shows each table's type
- Poker AI written from scratch (server/ai.js, no libraries): fast 7-card
  evaluator (checked against bestHand), Monte Carlo equity, and decisions from
  hand rank, pot odds, raise count, opponents and a per-CPU style (aggression,
  bluff rate); continuation bets via the last aggressor. It never sees other
  players' hole cards
- CPU seats: think time of 0.7–1.8s (faster when no human is left in the hand),
  automatic rebuy, never the host, no new hand unless a human is playing,
  re-think after pause
- Play UI: robot avatars and a "考えています…" status for CPU turns
- Tests for the evaluator, equity, legality of AI actions and CPU tables

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

public/assets/create.js

@@ -16,8 +16,8 @@
   const timerInput = $('timer');
   const intervalInput = $('interval');
   const scheduleEl = $('schedule');
-  const cardsInput = $('cards');
-  const cardsHint = $('cards-hint');
+  const modeHint = $('mode-hint');
+  const cpuOptions = $('cpu-options');
   const blindHint = $('blind-hint');
   const errorEl = $('error');
   const submitBtn = $('submit');
@@ -68,16 +68,23 @@
       .join('');
   }
 
-  function updateCardsHint() {
-    cardsHint.textContent = cardsInput.checked
-      ? 'オン: 各自のスマホに手札が配られ、勝敗とポットの分配は自動'
-      : 'オフ: 実物のカードで遊び、ショーダウンの勝者はホストが選ぶ';
+  const MODE_HINTS = {
+    chips: '実物のカードで遊び、サイトはチップだけを管理。ショーダウンの勝者はホストが選ぶ',
+    friends: '各自のスマホに手札が配られ、勝敗とポットの分配は自動',
+    cpu: 'CPU と対戦（友達も空いている席に参加できる）。カードの配布・勝敗の判定は自動',
+  };
+  const radioValue = (name) => (form.querySelector(`input[name="${name}"]:checked`) || {}).value;
+
+  function updateMode() {
+    const mode = radioValue('mode');
+    modeHint.textContent = MODE_HINTS[mode] || '';
+    cpuOptions.hidden = mode !== 'cpu';
   }
 
   function refresh() {
     updateHint();
     updateSchedule();
-    updateCardsHint();
+    updateMode();
   }
 
   stackInput.addEventListener('input', () => {
@@ -100,7 +107,7 @@
   });
   timerInput.addEventListener('change', refresh);
   intervalInput.addEventListener('input', refresh);
-  cardsInput.addEventListener('change', refresh);
+  form.querySelectorAll('input[type="radio"]').forEach((el) => el.addEventListener('change', refresh));
   $('reroll').addEventListener('click', suggestName);
 
   function validate() {
@@ -138,7 +145,8 @@
         bigBlind: int(bbInput),
         blindTimerEnabled: timerInput.checked,
         blindIntervalMin: int(intervalInput),
-        cardsEnabled: cardsInput.checked,
+        mode: radioValue('mode'),
+        cpuCount: Number(radioValue('cpu-count')),
         token: Store.token,
       });
       location.href = '/table/' + encodeURIComponent(id);