Add Nix flake

[TilCreator]

Add Nix flake

Checklist

• I have read the contribution guidelines

Summary

Allows easily using Keypeek on Nix and NixOS systems.

I want to use this software on my NixOS setup and encountered the issue that neither cargo run or the appimage worked.
My solution was to write a Nix build file for this project, this build file contains mostly boilerplate code to build a Rust project and all the required dependencies, the Rust crates are still only defined in the Cargo.toml.

I don't know if you are happy with merging this, especially if you might not want to maintain the build file.
If not I would still recommend to either keep this PR around as a draft PR or similar so that other users like myself can use and build upon this PR.

Related issue

Type of change

• Bug fix
• New feature
• UI change
• Documentation update
• Refactoring / maintenance

Testing

The resulting build was tested on NixOS 25.11 with a Sway WM and using a Totem split keyboard with ZMK firmware.

Screenshots or recordings

[srwi]

Hi, thank you for the PR! I haven't personally worked with NixOS before, but since this is quite an isolated addition, I think it's fine to merge it. Would it be possible to add a GitHub Actions workflow as well, so that we notice immediately if the Nix build starts to fail? I think I could probably keep it up to date then or another user could send another PR. 🙂

[TilCreator]

I will try to provide such a GitHub Action. It's my first time writing one from near scratch, so I will probably need a few attempts. ^^

The Nix Flake I used as a template includes some additional checks, which should I include in the Action or at all?

• building the package
• cargo clippy (warnings are treated as errors) [fails]
• cargo doc
• cargo fmt
• cargo audit [fails]
• cargo deny [fails]
• cargo nextest
• nix formatting using alejandra
• nix linting using deadnix and statix

[TilCreator]

For now I disabled all checks apart from the build, nextest and nix checks.

[srwi]

Cool, thank you for taking the challenge! Since it passes, I will merge it now. 🙂