fix live reload

[zugdev]

This is the same as in work.ubq.fi check this issue.

This repo's package.json start command uses wrangler pages to serve instead of esbuild-server:

"serve": "npx wrangler pages dev static --port 8080"

This killed the live reload feature, and according to this issue in wrangler's repo we have to pass in a directory after wrangler pages dev to hear changes from. Wrangler only looks specifically inside the directory given (non-recursive), in this case static, so even though HTML changes are captured, typescript ones aren't. Therefore it is extremely unreliable to get global ts changes. So I wrote an observer using esbuild API that watches and rebuilds based on file change. This spec might be a lil weird because I am extremely tired as I write it.