Add shared LNURL types, indexing helpers, and warnings.

Introduce lnurl as a first-class mint type with probe/announcement fields
and shared helpers the API and web can both rely on.

Co-authored-by: Cursor <cursoragent@cursor.com>

shared/src/nostr.ts

@@ -13,6 +13,15 @@ export const KIND_REVIEW = 38000;
 export const KIND_MINT_ANNOUNCEMENT = 38172;
 /** NIP-87 Fedimint federation announcement. */
 export const KIND_FEDIMINT_ANNOUNCEMENT = 38173;
+/**
+ * LNURL mint announcement.
+ *
+ * Not in NIP-87: this site's own proposed extension to it, specified in
+ * `docs/KIND-LNURL-MINT.md` and intended for a PR to nostr-protocol/nips. 38174 is the
+ * next free slot in the family — checked against the kind index in the nips README and
+ * against every issue and PR in that repository before it was claimed.
+ */
+export const KIND_LNURL_ANNOUNCEMENT = 38174;
 /** Profile metadata. */
 export const KIND_PROFILE = 0;
 
@@ -30,6 +39,7 @@ export const KIND_PROFILE = 0;
 export const ANNOUNCEMENT_KINDS = {
   cashu: KIND_MINT_ANNOUNCEMENT,
   fedimint: KIND_FEDIMINT_ANNOUNCEMENT,
+  lnurl: KIND_LNURL_ANNOUNCEMENT,
 } as const;
 
 /**
@@ -224,6 +234,11 @@ export function isFedimintReview(event: NostrEventLike): boolean {
   return tagValue(event.tags, 'k') === String(KIND_FEDIMINT_ANNOUNCEMENT);
 }
 
+/** True when the event's `k` tag marks it as being about an LNURL mint. */
+export function isLnurlReview(event: NostrEventLike): boolean {
+  return tagValue(event.tags, 'k') === String(KIND_LNURL_ANNOUNCEMENT);
+}
+
 /**
  * The kind a review says it is about, from its `k` tag, as a number.
  *