1.0 & nixpkgs release

[srid]

Before release

See sub-issues below for pending work.

Upstream

• @srid Release to crates.io
• Upstream pkgs.omnix to nixpkgs
  • Check: it installs the om binary (not omnix-cli).
  • Check: auto completion works on zsh (macOS) and bash (Linux)
  • Check: it builds on Intel mac
    • Even if upstream doesn't test x86_64-darwin in CI, we should manually make sure that our PR builds.

[srid]

Regarding release version of omnixrc:

The caller can now override the omnix invocation as of d25eab3

Once we release 1.0 to nixpkgs, we can host the stable omnixrc at https://ominx.page/omnixrc/1.0 (or some such versioned URL), which file would use nix run nixpkgs/<commithash>#omnix to fetch the pinned omnix.

When we release 1.1, we repeat the same process, allowing existings projects on 1.0 to remain unimpacted until they explicitly upgrade to 1.0 (by changing the URL and hash in their .envrc).