Host demo app [SBK-325]

[fubuloubu]

Add hosting for demo app against Sepolia deployment

Make sure it works in PRs so it's easier to review changes to the component lib

related to #53

[fubuloubu]

maybe use vercel

[mikeshultz]

For RAs to easily review PR changes.

[alexisnsns]

Now that we have working local installs we can give this another try

[fubuloubu]

Note that vercel still won't work without the ability to run ape compile

[mikeshultz]

I mentioned it in #69, but what if we just included the manifest in the source tree? We just commit updates when the contract changes. It's something that we would have to explicitly do which is a little annoying, but it should be rare. Then we don't need to compile anything during SDK builds.