Auto Author Acceptance Tests

Auto-flow skill — author executable acceptance tests from a ticket's acceptance criteria, after /plan has fixed the surface but INDEPENDENT of the implementation, then COMMIT them so they become the build's base. Invoked by /auto-dev-flow between planning and building. Picks the test type per criterion's LAYER (UI → Playwright + data-testids, logic → unit, API/service → integration, data → seeded-DB) rather than defaulting to the browser — auto-flow is general-purpose, not front-end-only. The builder must SATISFY these tests, never edit them — committing them first is what makes any later edit visible in the diff. Half of auto-flow's test-integrity defense (the other half…