CI: Add dedicated check and cachix workflows

.github/workflows/cachix.yml

@@ -0,0 +1,41 @@
+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: cachix
+
+on:
+  push:
+    branches:
+      - 'main'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+      - name: Install Nix
+        uses: cachix/install-nix-action@v27
+        with:
+          github_access_token: '${{ secrets.GITHUB_TOKEN }}'
+      - name: Enable Cachix
+        uses: cachix/cachix-action@v15
+        with:
+          name: doom-emacs-unstraightened
+          authToken: '${{ secrets.CACHIX_AUTH_TOKEN }}'
+      - name: Cache downloads
+        uses: ./.github/actions/cache-downloads
+      - name: Build packages for Cachix
+        run: nix build .#cachix-packages

.github/workflows/check.yml

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+# Copyright 2024 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+name: check
+
+on:
+  push:
+  pull_request:
+  workflow_dispatch:
+
+jobs:
+  check:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v4
+      - name: Install Nix
+        uses: DeterminateSystems/nix-installer-action@main
+      - name: Enable Magic Nix Cache
+        uses: DeterminateSystems/magic-nix-cache-action@main
+        with:
+          use-flakehub: false
+      - name: Cache downloads
+        uses: ./.github/actions/cache-downloads
+      - name: Check flake.lock
+        uses: DeterminateSystems/flake-checker-action@main
+      - name: nix flake check
+        run: nix flake check -L --show-trace