Non-blocking loading for better perceived performance

[JudahGabriel]

https://web.dev (and Chrome Lighthouse audit) shows poor performance for Chavah:

In particular, the time to first contentful paint, first meaningful paint, and time to interactive is all low. Part of the problem is rendering is blocked on our script tags.

While this is negligible on a fast connection, it can be a large delay of 7-10 seconds on slower mobile connections.

We should consider instead to show the Chavah splash immediately and load our scripts asynchronously.