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/public/sw.js

@@ -1,6 +1,6 @@
 /* Cyrene v2 PWA service worker — core-resource caching + offline shell. */
 const CACHE = "cyrene-web-v1";
-const PRECACHE = ["/", "/index.html", "/manifest.json", "/icon.svg"];
+const PRECACHE = ["/", "/index.html", "/manifest.json", "/images/Cyrene_Avatar/3rd_Form/Cyrene-3F-Q-Happy-1.png"];
 
 self.addEventListener("install", (event) => {
   event.waitUntil(