things I've changed from the PR:
- dropped legacy (i.e. non-flake) compat stuff, which turns out to account for most of the diff
- dropped `packages.garnet` since it doesn't work with `nix build .#garnet`
- back to using Rust-extended packages everywhere, which _seems_ fine
the rest is just re-inlining things and other refactors
note that changes we keep are essentially:
- not using Crane's extended packages everywhere
- bumping `nix-haskell` to avoid shell hook workaround
- various changes in how we call `nix-haskell`
- using `libCgarnet_rs` name, which Cabal expects
- adding proper non-dev-shell targets, so that e.g. `nix run` works
stuff we should still take a look at:
- seems a bit weird that `garnet-rs` arg to `project.nix` was always same (and therefore now we always pass the ) - might be a mistake, and we're supposed to be using local for local build?
- similar `libCgarnet_rs.a` logic appears in three places - see if we can deduplicate to some extent somehow
- I haven't even checked all steps are necessary
