Feat/openapi spec

[btwshivam]

What

Why

Fixes #

How

Testing

• make lint test passes locally
• go test -race ./... passes
• If a new rule: added a chart fixture in testdata/ and a golden output
• Tested locally with:

Checklist

• PR title follows Conventional Commits (feat(scope): subject)
• All commits are DCO-signed (git commit -s)
• No unrelated changes pulled in
• Documentation updated where user-visible behavior changed
• No LLM calls or telemetry introduced
• No proprietary backend imports