Produce build artifacts in CI

For the time being at least, at the time of releases, these will have to be manually attached to annotated tags per Sourcehut's documentation.

Signify presence of scripts with exit code

This also removes the output text when no scripts are found.

Add build status to README

Add CI tests

Running CI in Arch didn't work with ghcup, and with NixOS currently
using the same versions of everything (GHC 8.10.4, Cabal 3.4.0.0) it's
the easiest solution.

Hide -v from -h header

Minor refactor Solver fns

Represent scripts as a non-empty set

This prevents us from needing to think about duplicate scripts.

Remove ToolResult type; embrace Map

Use _ prefix notation for lenses

Formatting

Update -v text for consistency with -h

Add supported tooling to README

Add CI linting

No testing yet as the previous attempt via ghcup didn't work:
https://builds.sr.ht/~samhh/job/513082#task-test

0.1.0

Add GNU make support

Append scripts via lens

This is a lot of complexity to introduce to benefit a single call site, but I want to learn more about lenses. :)

Improve Yarn strategy, removing dependency upon npm

Implement more robust solver

Fix npm not displaying if there are no scripts

Add support for Spago