fix: admin 前端 base path 设为 /admin/ 修复资源加载路径

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

admin-frontend/vite.config.ts

@@ -3,6 +3,7 @@ import react from '@vitejs/plugin-react'
 import path from 'path'
 
 export default defineConfig({
+  base: '/admin/',
   plugins: [react()],
   resolve: {
     alias: {