ci(cachix): build nix env and cache results in cachix

.github/workflows/nix.yml

@@ -0,0 +1,40 @@
+name: Nix qmk env
+on:
+  workflow_dispatch:
+  push:
+    branches:
+      - main
+    paths:
+      - "**.nix"
+      - "flake.lock"
+      - "firmware/*"
+
+jobs:
+  build:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - os: ubuntu-latest
+            target: x86_64-linux
+          - os: macos-latest
+            target: x86_64-darwin
+    runs-on: ${{ matrix.os }}
+    steps:
+      - name: Setup | Checkout
+        uses: actions/checkout@v4
+
+      - name: Setup | Install nix
+        uses: cachix/install-nix-action@v23
+        with:
+          extra_nix_config: |
+            access-tokens = github.com=${{ secrets.GITHUB_TOKEN }}
+
+      - name: Setup | Install cachix
+        uses: cachix/cachix-action@v12
+        with:
+          name: edeneast-qmk-firmware
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+
+      - name: Build | Environment
+        run: nix build .#devShells.${{ matrix.target }}.default

.gitignore

@@ -5,4 +5,5 @@
 firmware/
 external/
 result/
+result
 wiki/

flake.nix

@@ -7,6 +7,15 @@
     };
   };
 
+  nixConfig = {
+    extra-substituters = [
+      "https://edeneast-qmk-firmware.cachix.org"
+    ];
+    extra-trusted-public-keys = [
+      "edeneast-qmk-firmware.cachix.org-1:lZ1aALkZD5qlipgrCqrJbYUAmwm6ED04fAnG23QqQaQ="
+    ];
+  };
+
   outputs = { self, nixpkgs, flake-utils }:
     flake-utils.lib.eachDefaultSystem (system:
       let