ci: add pre-commit and CI lint workflow (#9)

We introduce pre-commit hook with clang-format to
enforce a unified code style across the project,
reducing style discussions and speeding up cod
reviews.

ref: https://pre-commit.com/

.clang-format

@@ -0,0 +1,2 @@
+---
+BasedOnStyle: Google

.github/workflows/lint.yml

@@ -0,0 +1,31 @@
+name: Lint
+on:
+  push:
+    branches:
+      - '**'
+      - '!dependabot/**'
+    tags:
+      - '**'
+  pull_request:
+concurrency:
+  group: ${{ github.head_ref || github.sha }}-${{ github.workflow }}
+  cancel-in-progress: true
+permissions:
+  contents: read
+jobs:
+  pre-commit:
+    name: pre-commit
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - name: Install
+        run: |
+          python -m pip install pre-commit
+      - uses: actions/cache@v4
+        with:
+          path: ~/.cache/pre-commit
+          key: pre-commit-${{ hashFiles('.pre-commit-config.yaml') }}
+          restore-keys: pre-commit-
+      - name: Run
+        run: |
+          pre-commit run --show-diff-on-failure --color=always --all-files

.pre-commit-config.yaml

@@ -0,0 +1,5 @@
+repos:
+  - repo: https://github.com/pre-commit/mirrors-clang-format
+    rev: "v20.1.4"
+    hooks:
+      - id: clang-format