Add order expiration support to NIP-69

1. Added expires_at tag to track when pending orders should expire
2. Added expired as a new order status
3. Clarified the distinction between expires_at (for order expiration) and expiration (for relay deletion per NIP-40)

Author: grunch

src/order_event.md

@@ -35,7 +35,8 @@ Events are [addressable events](https://github.com/nostr-protocol/nips/blob/mast
     ["name", "Nakamoto"],
     ["g", "<geohash>"],
     ["bond", "0"],
-    ["expiration", "1719391096"],
+    ["expires_at", "1719391096"],
+    ["expiration", "1719995896"],
     ["y", "lnp2pbot"],
     ["z", "order"]
   ],
@@ -49,7 +50,7 @@ Events are [addressable events](https://github.com/nostr-protocol/nips/blob/mast
 - `d` < Order ID >: A unique identifier for the order.
 - `k` < Order type >: `sell` or `buy`. This specifies the type of transaction in terms of bitcoin. "sell" means selling bitcoin, while "buy" indicates buying bitcoin.
 - `f` < Currency >: The fiat asset being traded, using the [ISO 4217](https://en.wikipedia.org/wiki/ISO_4217) standard.
-- `s` < Status >: `pending`, `canceled`, `in-progress`, `success`.
+- `s` < Status >: `pending`, `canceled`, `in-progress`, `success`, `expired`.
 - `amt` < Amount >: The amount of Bitcoin to be traded, the amount is defined in satoshis, if `0` means that the amount of satoshis will be obtained from a public API after the taker accepts the order.
 - `fa` < Fiat amount >: The fiat amount being traded, for range orders two values are expected, the minimum and maximum amount.
 - `pm` < Payment method >: The payment method used for the trade, if the order has multiple payment methods, they should be separated by a comma.
@@ -61,7 +62,8 @@ Events are [addressable events](https://github.com/nostr-protocol/nips/blob/mast
 - `name` [Name]: The name of the maker.
 - `g` [Geohash]: The geohash of the operation, it can be useful in a face to face trade.
 - `bond` [Bond]: The bond amount, the bond is a security deposit that both parties must pay.
-- `expiration` < Expiration\>: The expiration date of the order ([NIP-40](https://github.com/nostr-protocol/nips/blob/master/40.md)).
+- `expires_at` < Expires At\>: The expiration date of the event being published in `pending` status, after this time the event status SHOULD be changed to `expired`.
+- `expiration` < Expiration\>: The expiration date of the event, after this time the relay SHOULD delete it ([NIP-40](40.md)).
 - `y` < Platform >: The platform that created the order.
 - `z` < Document >: `order`.
 
@@ -74,6 +76,8 @@ Currently implemented on the following platforms:
 - [Mostro](https://github.com/MostroP2P/mostro)
 - [@lnp2pBot](https://github.com/lnp2pBot/bot)
 - [Robosats](https://github.com/RoboSats/robosats/pull/1362)
+- Peach
+- Hodlhodl
 
 ## This document is inspired on