Docs: API_REFERENCE + ARCHITECTURE updated to the owner-chosen email-match association model (incl. anonymous, tradeoff documented) and listMemberSubmissions; HANDOFF pass-32; corrected pass-31 header. Landing: tightened the <=600px breakpoint (nav/section/card padding) and added a <=400px block so the nav fits ~320px without overflow. CSS-only inside media queries; desktop unchanged.