Replace eslint with biome

[mattt]

From biomejs.dev:

One toolchain for your web project
Format, lint, and more in a fraction of a second

Biome not only lives up to that promise, but has fewer (i.e. no) dependencies, less configuration, and introduces more and more useful warnings.

$ time npm run lint

> [email protected] lint
> biome lint .

Checked 16 file(s) in 19ms

________________________________________________________
Executed in  400.36 millis    fish           external
   usr time  206.32 millis    4.13 millis  202.19 millis
   sys time  119.15 millis    2.02 millis  117.13 millis

[mattt]

Merging with rebase so that I can configure 2160cf7 to be ignored for git blame.