ci: add pre-commit hooks and GitHub Actions workflow

- Add .pre-commit-config.yaml with ruff and pre-commit-hooks
- Add CONTRIBUTING.md with coding style guidelines
- Add GitHub Actions workflow for automatic pre-commit checks on PR and push

Author: Harahan

.github/workflows/pre-commit.yml

@@ -0,0 +1,19 @@
+name: pre-commit
+
+on:
+  pull_request:
+  push:
+    branches: [main]
+
+jobs:
+  pre-commit:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-python@v5
+        with:
+          python-version: '3.10'
+      - name: Install pre-commit
+        run: pip install pre-commit
+      - name: Run pre-commit
+        run: pre-commit run --all-files

.pre-commit-config.yaml

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+# Follow https://verdantfox.com/blog/how-to-use-git-pre-commit-hooks-the-hard-way-and-the-easy-way
+repos:
+  - repo: https://github.com/astral-sh/ruff-pre-commit
+    rev: v0.11.0
+    hooks:
+      - id: ruff
+        args: [--fix, --respect-gitignore, --config=pyproject.toml]
+      - id: ruff-format
+        args: [--config=pyproject.toml]
+
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v4.5.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-toml
+      - id: check-added-large-files
+        args: ['--maxkb=3000']  # Allow files up to 3MB
+      - id: check-case-conflict
+      - id: check-merge-conflict
+      - id: debug-statements

CONTRIBUTING.md

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+## Contributing Guidelines
+
+### Coding Style Guide
+
+In general, we adhere to [Google Python style guide](https://google.github.io/styleguide/pyguide.html), and we recommend to use `yapf` to format your code.
+
+In this project, we adopted `pre-commit` to automatic check the code style.
+
+To begin with, you should follow the step below to install `pre-commit`.
+
+```bash
+pip install pre-commit
+```
+
+Then, you should config the pre-commit hook as below.
+
+```bash
+pre-commit install
+```
+
+Then when you commit your change, your code will be automatically checked.