README covers:
- What the extension is / isn't (CMS only; customer UI in webapp;
no festival entity; no central splitter)
- Architecture diagram
- Data model summary
- Order state machine
- Nostr (kind 0 / 30402 / 5; NIP-17 stub)
- Public vs owner-write API surface
- A worked-out webapp integration snippet showing the multi-
restaurant cart flow (group by restaurant -> per-restaurant
quote -> sufficient-balance check -> N place_order calls ->
pay each bolt11)
- Install instructions for development
- Roadmap of explicitly-deferred items (NIP-44 unwrap, per-
restaurant secret storage, SSE/push, HODL atomicity, foreign
menu cache, image upload pipeline)
