fix: align website with unified execution

Remove obsolete work-mode labels from bilingual product previews and describe tools through enabled capabilities and Runtime assignments. Fix preview overlap and narrow-screen clipping, guard the updated copy, and record execution migration and validation results.

Release note: 官网同步移除 Ask/Execute 模式展示，更新工具配置说明，并修复桌面与手机首屏示意的遮挡和裁切。

sites/index.html

@@ -190,7 +190,7 @@
                       <strong>修复搜索空结果</strong>
                       <span>项目：知识检索</span>
                     </div>
-                    <div class="mode-pill">Continue · 执行</div>
+                    <div class="runtime-pill">Continue</div>
                   </div>
                   <div class="message-area">
                     <div class="message message--user">搜索词带空格时没有结果，请修复并补充测试。</div>
@@ -217,12 +217,12 @@
                   </div>
                   <div class="composer">
                     <span>描述你想完成的编程任务…</span>
-                    <div class="composer-actions"><span>执行</span><b>↑</b></div>
+                    <div class="composer-actions"><span>Continue</span><b>↑</b></div>
                   </div>
                 </div>
               </div>
             </div>
-            <div class="floating-card floating-card--approval">
+            <div class="floating-card floating-card--agents">
               <span class="floating-icon">
                 <svg viewBox="0 0 24 24" aria-hidden="true"><path d="m8 7-5 5 5 5M16 7l5 5-5 5M14 4l-4 16" /></svg>
               </span>
@@ -462,7 +462,7 @@
               </div>
               <span class="feature-number">04</span>
               <h3>直接提问或交付任务</h3>
-              <p>无需切换工作模式。可用工具由所选 Runtime 和已启用能力决定，操作使用当前账号权限，工具调用保留在运行记录中。</p>
+              <p>可用工具由所选 Runtime 和已启用能力决定。你可以在设置中管理 MCP 服务及其 Runtime 分配，操作使用当前账号权限，工具调用保留在运行记录中。</p>
             </article>
 
             <article class="feature-card">