P0 fixes from UX_AUDIT_2026-10-09.md:
- useMarketplaceItem now filters admin-hidden listings and skips
showcase-only (not-for-sale) items, so a direct /listing/... URL cannot
surface removed or non-sale content.
- Listing detail hides Make an offer for logged-out users and for
fixed-price listings (Buy is the single primary CTA there).
Borrowed from the Plebeian market review: a /marketplace-guidelines page
(peer-to-peer, buyer-beware, no checkout, prohibited items, soft
moderation), linked from the marketplace hub; new marketTerms en/es keys.
Records the remaining borrowables in the audit doc.
Full app audit (UX_AUDIT_2026-10-09.md), heavy on the marketplace flow
sequence. Headline verified findings: useMarketplaceItem does not filter
admin-hidden or exclude showcase-only listings (a hidden/not-for-sale
listing is reachable by URL); the buyer CTAs compete on fixed-price
listings and Make an offer is shown to logged-out users; the grid's Mark
as sold skips MarkSoldDialog so no trade attestation is recorded; the hub
tabs are not URL-addressable; nav.marketplace and nav.trades are
duplicate labels; and the nav customizer Reset hardcodes 3 tabs against
MIDDLE_SLOTS 4. Includes a recommended fix order. Audit only, no code
changes.
