workflows: Prepend reusable workfow with _

.github/workflows/_build-host.yml

@@ -0,0 +1,30 @@
+name: Build host
+on:
+  workflow_call:
+    inputs:
+      hosts:
+        required: true
+        type: string
+    secrets:
+      CACHIX_AUTH_TOKEN:
+        required: true
+jobs:
+  build-host:
+    name: ${{ matrix.host }}
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        host: ${{ fromJson(inputs.hosts) }}
+    steps:
+      - uses: actions/checkout@v6
+      - uses: cachix/install-nix-action@v31
+        with:
+          extra_nix_config: experimental-features = nix-command flakes pipe-operators
+      - uses: cachix/cachix-action@v16
+        with:
+          name: sebastian-stork
+          authToken: "${{ secrets.CACHIX_AUTH_TOKEN }}"
+          useDaemon: false
+      - name: Build host
+        run: nix build .#nixosConfigurations.${{ matrix.host }}.config.system.build.toplevel --print-build-logs