feat(session): add explicit leave and immediate slot release

web/index.html

@@ -13,15 +13,18 @@
     <header class="topbar">
       <a class="brand" href="/" aria-label="maze32, на главную">MAZE<span>32</span></a>
       <div class="connection-pill" id="connection" data-state="connecting" role="status"><span class="signal" aria-hidden="true"></span><span id="connection-text">Ловим сигнал ESP…</span></div>
+      <span class="quality-pill" id="quality" data-state="unknown" role="status" aria-live="polite" aria-label="Отклик неизвестен"><svg aria-hidden="true"><use href="/icons.svg#signal"></use></svg><span id="quality-text">—</span></span>
       <button class="icon-button" id="settings-toggle" type="button" aria-controls="settings-menu" aria-expanded="false" aria-label="Открыть настройки"><svg aria-hidden="true"><use href="/icons.svg#gear"></use></svg></button>
     </header>
     <aside class="settings-menu" id="settings-menu" hidden aria-label="Настройки">
       <strong>Настройки</strong>
       <span class="settings-details" id="details-text">Подключение ещё не готово.</span>
+      <span class="settings-quality" id="quality-details">Отклик: неизвестен</span>
       <button class="settings-item" id="settings-mute" type="button" aria-pressed="false" hidden>Звук: вкл</button>
       <button class="settings-item" id="settings-motion" type="button" aria-pressed="false" hidden>Движение: вкл</button>
       <button class="settings-item" id="settings-help" type="button" hidden>Показать обучение</button>
       <a class="settings-item" id="settings-wifi" href="/provision">Настроить Wi‑Fi</a>
+      <button class="settings-item settings-exit" id="settings-leave" type="button" hidden>Выйти из игры</button>
     </aside>
 
     <section class="screen welcome-screen" id="welcome-screen" aria-labelledby="welcome-title">
@@ -86,6 +89,7 @@
   </main>
 
   <div class="modal" id="modal" hidden role="dialog" aria-modal="true" aria-labelledby="modal-title"><div class="modal-card"><svg id="modal-icon" aria-hidden="true"><use href="/icons.svg#hourglass"></use></svg><p class="eyebrow" id="modal-kicker">Серверное объявление</p><h2 id="modal-title">Приготовились!</h2><div class="countdown" id="countdown" hidden>3</div><p id="modal-text">Один сервер — один честный момент.</p><button class="button primary" id="modal-action" type="button" hidden>Вернуться в лобби</button></div></div>
+  <section class="modal" id="leave-confirmation" hidden role="dialog" aria-modal="true" aria-labelledby="leave-title"><div class="modal-card"><p class="eyebrow">Подтверждение</p><h2 id="leave-title">Выйти из игры?</h2><p id="leave-text"></p><div class="button-row"><button class="button primary" id="leave-accept" type="button">Выйти</button><button class="button" id="leave-cancel" type="button">Остаться</button></div></div></section>
   <script src="/player.js" defer></script>
 </body>
 </html>