[dev] Provide pre-commit hooks for local validation

[bjosv]

Currently, several checks are only enforced in CI. This means contributors might only discover issues (formatting, linting, or other policy checks) after pushing a commit and waiting for CI to run.

Proposal:
Provide a recommended setup using Git Hooks to run a subset of the checks before commits are created. This would allow contributors to run the same validations locally and catch issues earlier.

Implementation alternatives:

• Provide a recommended .pre-commit-config.yaml that runs a subset of the checks currently enforced in CI before commits are created.
  Add instructions in CONTRIBUTING.md how to setup pre-commit.

• Provide a script that can be used and document the setup in CONTRIBUTING.md.

• ... (other alternatives?)

See: #109 (comment)