stardust:qa — read-only site QA sweep

One live URL in. One evidence-bound findings report out. This skill never edits anything — not site content, not DA documents, not repo code. Its only writes are report artifacts under stardust/qa/. If the user wants findings fixed, that is a separate, explicit follow-up outside this skill.

qa is the post-deploy counterpart of rollout's delivery verification: where rollout asks "did every page ship?", qa asks "is everything that shipped actually correct?" — at all three layers a deploy can silently break:

1. delivery — what the pipeline serves (.plain.html, full HTML, sheets, sitemap)
2. rendered — what a browser shows after block decoration
3. regression — what changed since the last approved state (visual baselines)

A green upper layer never implies the lower one: a publish 200 ≠ delivered, delivered HTML ≠ rendered correctly.

Setup