[Toybox] Shell Compatibility Reports from Oils - ~800 tests passing

[Andy Chu]

> (Coding is easy. Figuring out what it's supposed to DO has always been
> the hard part.)

I agree!

And to repeat, that's what I'm saying OSH has already done.  It's the
most bash-compatible shell, by far -
https://pages.oils.pub/spec-compat/2025-06-26/renamed-tmp/spec/compat/PASSING.html

So I think sharing some labor rather than producing 4 different shells
is a good idea ... e.g. in particular OSH has some holes on the
interactive side, and we need to test it building real distros.

And we have a budget of 50 K euros for the next 6-12 months.  I
realized that reducing test cases from real distro shell scripts
(Alpine, Nix) is now a bottleneck.  That is, we have plenty of
isolated tests, but it's better to PRIORITIZE those by what actually
happens in the wild.

Andy