Review follow-ups:
- Each contact_consent event carries a rev that goes up with every change,
sends are serialized, and `contacts` picks every field from the highest
rev per copy, so a withdrawal can't lose to an earlier event sent in the
same second or with a skewed clock.
- Removing the address also replaces it with <removed> in the local
sent log (earlier contact events and problem reports).
- The prompt is rechecked when the Frame connects, not only at page load.
- No thanks hides the bar only once the dismissal is saved.
- docs/privacy.md: say that the analytics switches don't block a report or
contact change the person sends deliberately.
Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
