feat(users/flokli/keyboard): init

This packages up my keyboard firmware used for the Keychron K6 Pro.

We add a custom keymap to the `keyboards/keychron/k6_pro/ansi/rgb/
keymaps` directory, a copy from the `default` one (with a modified
`keymap.c`), and then build that as a makefile target.

`via` is *disabled*, as their keybindings take priority over keymap.c.

Luckily, only `qmk` seems to be sufficient to build it.

A simple `:flash` target/script is provided as well, it relies on some
udev rules set in the global system
(`hardware.keyboard.qmk.enable = true`).

Change-Id: I9f7a7a992e13516c32033127f94e37aec62d6b67
Reviewed-on: https://cl.tvl.fyi/c/depot/+/10020
Reviewed-by: flokli <flokli@flokli.de>
Tested-by: BuildkiteCI

users/flokli/keyboard/default.nix

@@ -0,0 +1,39 @@
+{ depot, pkgs, ... }:
+
+rec {
+  firmware = pkgs.stdenv.mkDerivation {
+    name = "keychron-k6_pro-firmware";
+
+    src = pkgs.fetchFromGitHub {
+      owner = "Keychron"; # the Keychron fork of qmk/qmk_firmware
+      repo = "qmk_firmware";
+      rev = "e0a48783e7cde92d1edfc53a8fff511c45e869d4"; # bluetooth_playground branch
+      hash = "sha256-Pk9kXktmej9JyvSt7UMEW2FDrBg7k1lOssh6HjrP5ro=";
+      fetchSubmodules = true;
+    };
+
+    nativeBuildInputs = [
+      pkgs.qmk
+    ];
+
+    buildPhase = ''
+      mkdir -p keyboards/keychron/k6_pro/ansi/rgb/keymaps/flokli
+      cp ${./keymap.c} keyboards/keychron/k6_pro/ansi/rgb/keymaps/flokli/keymap.c
+      cp ${./rules.mk} keyboards/keychron/k6_pro/ansi/rgb/keymaps/flokli/rules.mk
+
+      make keychron/k6_pro/ansi/rgb:flokli
+    '';
+
+    installPhase = ''
+      mkdir -p $out
+
+      cp keychron_k6_pro_ansi_rgb_flokli.bin $out/
+    '';
+  };
+
+  flash = pkgs.writeShellScript "flash.sh" ''
+    ${pkgs.qmk}/bin/qmk flash ${firmware}/keychron_k6_pro_ansi_rgb_flokli.bin
+  '';
+
+  meta.ci.targets = [ "firmware" ];
+}