feat(vite-plugin): add build.rewriteBase for remote miniapps

[Gaubee]

Summary

• Add server/build config structure to RemoteMiniappConfig for dev/build mode separation
• Implement rewriteHtmlBase() function to inject <base> tag in index.html
• Apply base rewrite after copying to dist (build mode only)
• Configure rwa-hub with build.rewriteBase: true

Problem

Remote miniapps like rwa-hub are built with base: '/' but deployed under /miniapps/rwa-hub/. This causes all relative resource paths to break (404 errors for /assets/xxx.js).

Solution

In build mode, after copying the remote miniapp to dist, rewrite index.html to inject:

<base href="/miniapps/rwa-hub/">

This makes all relative paths resolve correctly.

Configuration

remoteMiniappsPlugin({
  miniapps: [
    {
      metadataUrl: '...',
      dirName: 'rwa-hub',
      build: {
        rewriteBase: true,  // auto-infer '/miniapps/rwa-hub/'
        // or: rewriteBase: '/custom/path/'
      },
    },
  ],
})

Next Steps

After this PR is merged, PR2 will add wujie runtime support with similar server.runtime / build.runtime configuration.