Publish health: pre-publish accessibility + quality audit chip

The "Publish check" pill in the editor toolbar runs a structural audit on the current page every time you edit. The badge color reflects the highest severity:
• ✓ Healthy (emerald) — no issues
• 1+ tip (blue) — non-blocking suggestions
• 1+ warning (amber) — fixable quality issues
• 1+ critical (red) — should not ship like this

Click the chip to open the findings panel.

Critical checks:
• No top-level heading — every page needs a Hero or Section Header block (screen readers + search engines depend on it)
• Image missing alt text — accessibility breaker; visitors using screen readers can't navigate it
• Form has no notify destination or webhook — submissions land in the Inbox but nobody is alerted

Warning checks:
• Default placeholder copy still in place ("Welcome", "Your tagline goes here.", "Section Title")
• Hero overlay opacity below 0.2 over a background image — text may be unreadable on bright photos
• FAQ row has a question but no answer

Tip checks:
• Heading over 90 characters — likely to wrap on mobile
• Text block over 2000 characters — visitors rarely read past 800; consider splitting
• No way for visitors to contact you anywhere on the page (no Form, Reservation, CTA, etc.)

Jump to block:
Each finding with a specific block has a "Jump to block →" button — one click selects the offending block so the inspector opens to it. Findings of the same kind dedupe into one entry ("Image missing alt text (and 4 more)") so a page with 5 alt-less images doesn't crowd you with 5 separate rows.

The chip is informational — publish is never blocked by it. The closing note on the panel says it best: "publish still works, but critical issues like missing alt text and undirected forms cost you visitors. Fix what you can, publish what's ready."