Add docs for blossom, add nip 86 and 98 support

packages/util/src/Nip98.ts

@@ -0,0 +1,20 @@
+import {Base64} from "js-base64"
+import {sha256, textEncoder} from "@welshman/lib"
+import {makeEvent, SignedEvent} from "./Events.js"
+import {HTTP_AUTH} from "./Kinds.js"
+
+export const makeHttpAuth = async (url: string, method = "GET", body?: string) => {
+  const tags = [
+    ["u", url],
+    ["method", method],
+  ]
+
+  if (body) {
+    tags.push(["payload", await sha256(textEncoder.encode(body))])
+  }
+
+  return makeEvent(HTTP_AUTH, {tags})
+}
+
+export const makeHttpAuthHeader = (event: SignedEvent) =>
+  `Nostr ${Base64.encode(JSON.stringify(event))}`