feat: add unified contest pool and realtime game modes

backend/templates/index.html

@@ -175,9 +175,11 @@
       </section>
 
       <section class="view" id="view-contest">
-        <div class="page-title"><span class="kicker">CONTEST ARENA</span><h1>比赛</h1><p>实时 1v1、今日挑战和单人闯关，按水平赛道独立计算。</p></div>
-        <div class="track-switch" id="track-switch">
-          <button class="active" data-track="standard">标准</button><button data-track="beginner">入门</button><button data-track="advanced">进阶</button>
+        <div class="page-title"><span class="kicker">CONTEST ARENA</span><h1>比赛</h1><p>不再按难度拆分玩家池。选择玩法后即可随机匹配或用联机码约战。</p></div>
+        <div class="match-mode-switch" id="match-mode-switch" aria-label="实时比赛玩法">
+          <button class="active" data-match-mode="quiz"><b>口算竞速</b><small>同题抢分</small></button>
+          <button data-match-mode="sudoku"><b>数独 Timerun</b><small>正确完成者比时间</small></button>
+          <button data-match-mode="twenty_four"><b>24 点竞速</b><small>最先组出 24</small></button>
         </div>
         <section class="challenge-panel">
           <div>
@@ -186,7 +188,7 @@
             <p>创建 6 位联机码发给朋友，或输入朋友的联机码加入同一场对局。</p>
           </div>
           <div class="challenge-actions">
-            <button id="challenge-create" class="primary-button">创建当前赛道约战</button>
+            <button id="challenge-create" class="primary-button">创建口算竞速约战</button>
             <form id="challenge-join-form">
               <input id="challenge-code-input" maxlength="6" autocomplete="off" placeholder="输入 6 位联机码" aria-label="联机码">
               <button class="dark-button" type="submit">加入约战</button>