Demo intro anchoring image

Extended skill demo-site-wiring: mandatory page order now includes exactly one anchoring screenshot or contextual mockup in the suite/hub lede (with/after lay description, before variant switcher). Not a gallery; not competing heroes.

Complements identity strip / VCS logo / lay description / variant switcher; does not replace them.

Grandfather unchanged: apply on create / substantive intro edit; do not mass-retrofit old demos.

Pointer in agents/demos-and-push.md and thin line in AGENTS.md.