fix(web): 项目主图标统一替换为昔涟3rd_Form-Cyrene-3F-Q-Happy-1.png

- favicon/apple-touch-icon (index.html)
- PWA manifest 图标 (manifest.json)
- PWA precache (sw.js)
- 用户端侧栏品牌头像 (Nav.tsx)
- 管理面板顶栏品牌头像 (AdminApp.tsx)
- 删除已被替换的 icon.svg 残留引用

frontend/web/index.html

@@ -6,8 +6,8 @@
     <meta name="theme-color" content="#161616" />
     <meta name="description" content="Cyrene v2 用户前端（M9 模态 UI）" />
     <link rel="manifest" href="/manifest.json" />
-    <link rel="icon" type="image/png" href="/images/Cyrene_Avatar/2nd_Form/Cyrene-2F-N-Happy-1-192x192.png" />
-    <link rel="apple-touch-icon" href="/images/Cyrene_Avatar/2nd_Form/Cyrene-2F-N-Happy-1-192x192.png" />
+    <link rel="icon" type="image/png" href="/images/Cyrene_Avatar/3rd_Form/Cyrene-3F-Q-Happy-1.png" />
+    <link rel="apple-touch-icon" href="/images/Cyrene_Avatar/3rd_Form/Cyrene-3F-Q-Happy-1.png" />
     <title>Cyrene · 昔涟</title>
   </head>
   <body>