feat: asciinema with custom glyph font

[vonPB]

Usage

Place your .cast file in static/casts.

Now you can simply use the following in any markdown file:

# Installation

<Asciinema src="/casts/example.cast" rows={50} idleTimeLimit={3} preload={true} />

# Pre.....

Icon issues

if some custom icons are not appearing restart the dev server. This will re-run a script extracting the icons needed from all .cast files.

Performance

The custom font function used on build (only at startup for dev) is not quite as efficient in regards to size as the orginal in py, but should still good enough for now (11,1kb vs 4,7kb).