Implement Texas Hold'em play: dealing, betting, side pots, showdown

- Hand engine (server/hand.js): crypto-shuffled deck kept server-side,
  blinds (heads-up button = SB), min-raise rules incl. incomplete all-in,
  uncalled bet refunds, side pots, split pots, all-in runout
- Hand evaluator (server/cards.js) and node:test suite (npm test)
- Table flow: hands auto-continue after host START, 30s action clock
  (timeout = check/fold + sit out), sit out / sit in, rebuy, mid-hand leave
  folds and keeps the seat reserved until the hand ends, pause freezes all clocks
- Only each player's own hole cards are sent until a showdown/runout reveal;
  all actions validated server-side
- Play UI: board, hole cards, bets, action tags, turn timer, raise panel with
  presets, showdown results with winning cards highlighted, compact 7+ layout
- Remove the host crown and the temporary "next phase" control

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

server/index.js

@@ -216,18 +216,27 @@ io.on('connection', (socket) => {
     changed(table);
   });
 
-  // ホスト操作・退席は同じ形で処理する
+  // プレイヤー操作・ホスト操作は同じ形で処理する（操作者は join 時のトークンで決まる）
+  const ACTION_TYPES = new Set(['fold', 'check', 'call', 'raise']);
   const actions = {
     'table:leave': (t, token) => (t.leave(token) ? null : '着席していません'),
     'table:start': (t, token) => t.start(token),
-    'table:nextPhase': (t, token) => t.nextPhase(token),
     'table:pause': (t, token) => t.togglePause(token),
+    'table:action': (t, token, p) => {
+      if (!p || typeof p !== 'object' || !ACTION_TYPES.has(p.type)) return '不正なアクションです';
+      const amount = p.type === 'raise' ? p.amount : 0;
+      if (!Number.isSafeInteger(amount)) return '額が不正です';
+      return t.act(token, p.type, amount);
+    },
+    'table:sitOut': (t, token) => t.setSittingOut(token, true),
+    'table:sitIn': (t, token) => t.setSittingOut(token, false),
+    'table:rebuy': (t, token) => t.rebuy(token),
   };
   for (const [event, fn] of Object.entries(actions)) {
-    socket.on(event, (_p, ack) => {
+    socket.on(event, (p, ack) => {
       const table = socket.data.tableId && tables.get(socket.data.tableId);
       if (!table) return reply(ack, { ok: false, error: 'NOT_FOUND' });
-      const error = fn(table, socket.data.token);
+      const error = fn(table, socket.data.token, p);
       reply(ack, error ? { ok: false, error } : { ok: true });
       if (!error) changed(table);
     });
@@ -239,13 +248,13 @@ io.on('connection', (socket) => {
   });
 });
 
-// ブラインドタイマー
+// ブラインドタイマー・持ち時間・次のハンドなど時間で進む処理
 setInterval(() => {
   const now = Date.now();
   for (const table of tables.tables.values()) {
     if (table.tick(now)) changed(table);
   }
-}, 1000);
+}, 250);
 
 // 誰も見ていないテーブルを片付ける
 setInterval(() => {