#14064 feat(unit-based): release and document

Summary

@pieterbeulque I asked the agent to write the docs and rewrote / erased some parts. It should be compliant with Polar tone but please do review and propose copy update :)

@strandhvilliam happy to take your feedbacks as well since you developed most of it !

Checklist

• This PR addresses a single concern (one bug fix, one feature, one refactor)
• The diff is reasonably sized and easy to review
• New functionality is covered by tests
• Linting and type checking pass (uv run task lint && uv run task lint_types)
• No unrelated changes or drive-by fixes are included