Resolve "Coverage: Artifacts and branches" ✨️

Closes #25 🐔️👍️
Approved-by: loutr <loutr@crans.org>

🦀️🍰🦀️🍰🦀️🍰

* fix(flake): Correctly interlink inputs

* chore: Add coverage folder into gitignore

* feat(ci): Output only branches in CI-view

* feat(nix): Add coverage command with devshell

* feat(ci, nix): Branches coverage