Nix flake with devShell providing qmk CLI for firmware development.
Custom keymap (copy of default) symlinked into QMK tree on shell entry.
Setup: nix develop, then qmk setup system76/qmk_firmware
Build: qmk compile -kb system76/launch_3 -km custom
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
