Track test coverage

[jbmoelker]

User stories

As an developer authoring or reviewing Head Start,
I want to see how well code changes are covered,
so that I know how well new code is tested.

As a developer using Head Start,
I want to see how well the code base is tested,
so that I'm reassured and more confident in using Head Start for my project.

Approach

• Use https://github.com/davelosert/vitest-coverage-report-action ?
• Set thresholds for directories? (Like very high for lib/ )
• Use coverage mode changes only?
• Use compare mode to see trend with main branch?