fix(portal): replace 404 iterm2.png with valid google-gemini.png icon for AGY

stacks/portal/index.html

@@ -508,7 +508,7 @@
       <div class="w-full h-full max-w-6xl hl-card flex flex-col overflow-hidden shadow-2xl">
         <div class="px-4 py-2.5 border-b hl-border flex items-center justify-between hl-muted">
           <div class="flex items-center gap-2.5">
-            <img src="https://cdn.jsdelivr.net/gh/walkxcode/dashboard-icons/png/iterm2.png" class="w-4 h-4" />
+            <img src="https://cdn.jsdelivr.net/gh/walkxcode/dashboard-icons/png/google-gemini.png" class="w-4 h-4" />
             <span class="text-xs font-mono-num font-medium">AGY 云端工作台 · tmux 持久会话 (关窗不断连)</span>
           </div>
           <div class="flex items-center gap-2">
@@ -637,7 +637,7 @@
                   id: 'agy',
                   title: 'AGY 云端工作台',
                   subtitle: 'agy.961504.xyz · ttyd + tmux',
-                  iconUrl: 'https://cdn.jsdelivr.net/gh/walkxcode/dashboard-icons/png/iterm2.png',
+                  iconUrl: 'https://cdn.jsdelivr.net/gh/walkxcode/dashboard-icons/png/google-gemini.png',
                   online: t.services.agy,
                   actionType: 'drawer',
                   desc: 'M6 Mac mini 上的 24 小时常驻 AI 编程终端，已同步 Google 登录态并锁定新加坡出口，关掉网页后台继续运行。',