ci: add nix build (#126)

Author: adamcstephens

.github/workflows/ci-nix.yml

@@ -0,0 +1,29 @@
+name: Nix CI
+
+on:
+  pull_request:
+  push:
+    branches:
+      - main
+
+permissions:
+  contents: read
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    name: Nix Build
+
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@08c6903cd8c0fde910a37f88322edcfb5dd907a8 # v5.0.0
+
+      - name: Install Nix
+        uses: cachix/install-nix-action@7be5dee1421f63d07e71ce6e0a9f8a4b07c2a487 # v31.6.1
+
+      - name: Setup Nix GHA Cache
+        uses: DeterminateSystems/magic-nix-cache-action@565684385bcd71bad329742eefe8d12f2e765b39 # v13
+
+      - name: Build
+        run: |
+          nix build .#expert

.github/workflows/ci.yml

@@ -3,7 +3,8 @@ name: Elixir CI
 on:
   pull_request:
   push:
-    branches: main
+    branches:
+      - main
 
 env:
   DEFAULT_ELIXIR: 1.15.8-otp-25