Selling seats + booths from the floor plan

Once you've designed your event's seating chart or trade-show layout in the Layout tab, you can flip any table, chair row, or booth to "sellable" — attendees pick exact seats during ticket checkout, vendors pick their booth lots from a magic-link page.

How to enable selling:
1. Layout tab → drop tables / chair rows / booths on the venue's floor plan
2. Right-side panel → pick an overlay → toggle "Sellable"
3. Set per-unit price, tier label, and (for attendee seats) optional ticket-type restriction
4. Click "Materialize seats" in the toolbar — creates the addressable unit docs

The /events/:eventId/pick-seats page (and Venue Seat Picker Builder block) shows the floor plan with seats color-coded. Buyer picks N seats matching their ticket count → 10-min hold → checkout. On payment, seats flip to taken with the buyer's ticket id stamped.

For booths: Layout tab → "Invite vendor" → enter email + restrict to specific tiers/booths → magic link emails. They click → pick a booth → claim. Vendor record auto-created on the event.

Refunded tickets auto-release their seats. Admin can block seats for ADA / comp / VIP holds.