feat(web): support classic Rsbuild dev and build

- migrate the classic frontend from Vite to Rsbuild with JSX, Semi UI, proxy, and production build config.
- update make dev-web to run both default and classic frontends for local theme switching.
- fix classic public page height, footer, CORS proxy, error handling, and constant export warnings.
- update Dockerfile and release workflow to install from the web workspace root with the shared lockfile.

web/classic/src/pages/NotFound/index.jsx

@@ -28,7 +28,7 @@ import { useTranslation } from 'react-i18next';
 const NotFound = () => {
   const { t } = useTranslation();
   return (
-    <div className='flex justify-center items-center h-screen p-8'>
+    <div className='classic-page-fill flex justify-center items-center p-8'>
       <Empty
         image={<IllustrationNotFound style={{ width: 250, height: 250 }} />}
         darkModeImage={