pre-commit hooks for local validation

[sandeepkunusoth]

Fixes #111

Summary

Add local pre-commit validation support and contributor guidance for running checks before opening a PR.

Changes

• Added .pre-commit-config.yaml
• Documented pre-commit setup in CONTRIBUTING.md
• Added PR template with a reminder to run pre-commit locally

Testing

Ran:

pre-commit run --all-files
generate code and manifests..............................................Passed
run go mod tidy..........................................................Passed
run golangci-lint........................................................Passed
Check for merge conflicts................................................Passed

[stockholmux]

I haven't reviewed this in detail, but I think we should add a checkbox to the PR template to ask the contributor if they're run pre-commit hooks.

[jdheyburn]

Discussed in weekly meeting 2026-03-20. It was suggested that we could include a checkbox on the PR template (do we have a PR template?) to verify that pre-commit checks have been executed - as a "nudge" or reminder that these checks have been completed.

That should be non-blocking though. I had a couple of comments on here though.