promos.js (promo_codes + promo_redemptions, JSON fallback): create/update codes with
credits, partner, optional cap and expiry, on/off. Redeemed once per account either
from a join link ?promo=CODE (cookie, applied at signup) or the Overview box
'Have a promo code?' (/api/my/promo/redeem). Admin > Traffic gets a Partner promo
codes card (create, toggle, uses, recent redemptions). Chatbot line added.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>