NIP-99: add explicit callout for d and a tags/replaceable events

[alltheseas]

• Added an explicit requirement for the mandatory ["d", …] tag so kind:30402 listings actually behave as NIP-01 addressable events and can be fetched or replaced reliably across relays.
  • Documented how related events should reference listings via the ["a","::"] tag to keep cross-event linking interoperable.

[alltheseas]

cc @aceaspades

[staab]

This NIP isn't very well written, but this PR isn't really the solution. Kind 30402 isn't even explicitly defined here. https://github.com/nostr-protocol/nips/blob/master/17.md is an example of a more conventional way of introducing new kinds. It could be worth while re-writing this NIP to follow that format.

[luigi1256]

Kind 30402 isn't even explicitly defined here

it is probably defined in the extension GammaMarkets/market-spec

[staab]

@GammaMarkets would you be willing to open a PR to update this NIP? Are there any areas that your spec is incompatible with this one, or is it purely an extension? Do you have any idea of which clients implement which versions?