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/en.html

@@ -185,7 +185,7 @@
                       <strong>Fix empty search results</strong>
                       <span>Project: Knowledge search</span>
                     </div>
-                    <div class="mode-pill">Continue</div>
+                    <div class="runtime-pill">Continue</div>
                   </div>
                   <div class="message-area">
                     <div class="message message--user">Search returns nothing with extra spaces. Fix it and add tests.</div>
@@ -217,7 +217,7 @@
                 </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>
@@ -377,7 +377,7 @@
               </div>
               <span class="feature-number">04</span>
               <h3>Ask questions or give it a task</h3>
-              <p>No work-mode switch is needed. Available tools depend on the selected Runtime and enabled capabilities. Operations use the current account's permissions, and tool calls appear in the run history.</p>
+              <p>Available tools depend on the selected Runtime and enabled capabilities. Manage MCP services and their Runtime assignments in settings. Operations use the current account's permissions, and tool calls appear in the run history.</p>
             </article>
 
             <article class="feature-card">