Loading support

[kaaanata]

It took about 10s to load chunked js file.
You can add a loading page in index.html before virtual dom injected.

Here are three plans:

1. add a loading SVG motion in index.html.
2. add a "fake" progress bar in index.html.
3. replace source link in Wechat post to hack.hustunique.com, then prefetch resources in console.hack.hustunique.com via sourcemap.

[ttzztztz]

Nice issue, planning to fix this before Unique Hackday 2021 if it exists. :)