feat(frontend): improve favicon loading with fallback to config API

- Add synchronous config API call in index.html when localStorage cache is empty
- Prevents favicon flash on login page during first load
- Enhance getCachedConfigs() to fetch public configs as fallback
- Preserve existing siteConfig values when config keys are missing

vite-frontend/index.html

@@ -22,6 +22,35 @@
           cachedFavicon = '';
         }
 
+        // 无缓存时，尝试通过公开配置接口同步读取，避免登录页闪烁
+        if (!cachedFavicon.trim()) {
+          try {
+            const xhr = new XMLHttpRequest();
+            xhr.open('POST', '/api/v1/config/get', false);
+            xhr.setRequestHeader('Content-Type', 'application/json');
+            xhr.send(JSON.stringify({ name: 'app_favicon' }));
+
+            if (xhr.status === 200) {
+              const resp = JSON.parse(xhr.responseText || '{}');
+              const value =
+                resp &&
+                typeof resp === 'object' &&
+                resp.code === 0 &&
+                resp.data &&
+                typeof resp.data.value === 'string'
+                  ? resp.data.value.trim()
+                  : '';
+
+              if (value) {
+                cachedFavicon = value;
+                try {
+                  localStorage.setItem('vite_config_app_favicon', value);
+                } catch (_) {}
+              }
+            }
+          } catch (_) {}
+        }
+
         const faviconHref = cachedFavicon.trim() || defaultFavicon;
         let faviconLink = document.head.querySelector('link#app-favicon');