Introduce pre-commit hooks and update contribution guidelines

- Add `.pre-commit-config.yaml` with hooks for formatting, linting, and general file checks.
- Update `CONTRIBUTING.md` to include pre-commit setup instructions and emphasize automated checks during commits.
- Provide detailed steps for installing and running pre-commit hooks.

.pre-commit-config.yaml

@@ -0,0 +1,34 @@
+# Pre-commit hooks configuration
+# See https://pre-commit.com for more information
+
+repos:
+  # General file checks
+  - repo: https://github.com/pre-commit/pre-commit-hooks
+    rev: v5.0.0
+    hooks:
+      - id: trailing-whitespace
+      - id: end-of-file-fixer
+      - id: check-yaml
+      - id: check-toml
+      - id: check-merge-conflict
+      - id: check-added-large-files
+        args: ['--maxkb=1000']
+      - id: mixed-line-ending
+
+  # Rust formatting
+  - repo: https://github.com/doublify/pre-commit-rust
+    rev: v1.0
+    hooks:
+      - id: fmt
+        name: cargo fmt
+        description: Format Rust code with rustfmt
+      - id: cargo-check
+        name: cargo check
+        description: Check Rust code compilation
+      - id: clippy
+        name: cargo clippy
+        description: Lint Rust code with clippy
+        args: ['--all-features', '--', '-D', 'warnings']
+
+# Optional: run on all files when config changes
+default_install_hook_types: [pre-commit, pre-push]

CONTRIBUTING.md

@@ -32,15 +32,14 @@ Unsure where to begin contributing to Owlen? You can start by looking through `g
 The process for submitting a pull request is as follows:
 
 1.  **Fork the repository** and create your branch from `main`.
-2.  **Make your changes.**
-3.  **Ensure the code lints and formats correctly.**
-    - `cargo fmt --all`
-    - `cargo clippy --all -- -D warnings`
+2.  **Set up pre-commit hooks** (see [Development Setup](#development-setup) above). This will automatically format and lint your code.
+3.  **Make your changes.**
 4.  **Run the tests.**
     - `cargo test --all`
-5.  **Add a clear, concise commit message.** We follow the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) specification.
-6.  **Push to your fork** and submit a pull request to Owlen's `main` branch.
-7.  **Include a clear description** of the problem and solution. Include the relevant issue number if applicable.
+5.  **Commit your changes.** The pre-commit hooks will automatically run `cargo fmt`, `cargo check`, and `cargo clippy`. If you need to bypass the hooks (not recommended), use `git commit --no-verify`.
+6.  **Add a clear, concise commit message.** We follow the [Conventional Commits](https://www.conventionalcommits.org/en/v1.0.0/) specification.
+7.  **Push to your fork** and submit a pull request to Owlen's `main` branch.
+8.  **Include a clear description** of the problem and solution. Include the relevant issue number if applicable.
 
 ## Development Setup
 
@@ -52,6 +51,46 @@ cd owlen
 cargo build
 ```
 
+### Pre-commit Hooks
+
+We use [pre-commit](https://pre-commit.com/) to automatically run formatting and linting checks before each commit. This helps maintain code quality and consistency.
+
+**Install pre-commit:**
+
+```sh
+# Arch Linux
+sudo pacman -S pre-commit
+
+# Other Linux/macOS
+pip install pre-commit
+
+# Verify installation
+pre-commit --version
+```
+
+**Setup the hooks:**
+
+```sh
+cd owlen
+pre-commit install
+```
+
+Once installed, the hooks will automatically run on every commit. You can also run them manually:
+
+```sh
+# Run on all files
+pre-commit run --all-files
+
+# Run on staged files only
+pre-commit run
+```
+
+The pre-commit hooks will check:
+- Code formatting (`cargo fmt`)
+- Compilation (`cargo check`)
+- Linting (`cargo clippy --all-features`)
+- General file hygiene (trailing whitespace, EOF newlines, etc.)
+
 ## Coding Style
 
 -   We use `cargo fmt` for automated code formatting. Please run it before committing your changes.