code: Add clang-format target and CI workflow (#82)

* code: Add clang format target, rules and CI workflow

* code: Run clang format on sources

.github/workflows/format.yml

@@ -0,0 +1,21 @@
+name: Clang Format
+
+on:
+  push:
+    branches: [ "*" ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  clang-format:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          fetch-depth: 0
+      - name: Install
+        run: sudo apt-get install clang-format-15
+      - name: Build
+        env:
+          COMMIT_RANGE: ${{ github.event.pull_request.base.sha }}..${{ github.event.pull_request.head.sha }}
+        run: ./.ci/clang-format.sh