Announce nostr pubkey on lnurlp endpoint

app/controllers/lnurlpay_controller.rb

@@ -8,7 +8,7 @@ class LnurlpayController < ApplicationController
 
   # GET /.well-known/lnurlp/:username
   def index
-    render json: {
+    res = {
       status: "OK",
       callback: "https://#{Setting.accounts_domain}/lnurlpay/#{@user.cn}/invoice",
       tag: "payRequest",
@@ -17,6 +17,13 @@ class LnurlpayController < ApplicationController
       metadata: metadata(@user.address),
       commentAllowed: MAX_COMMENT_CHARS
     }
+
+    if Setting.nostr_enabled? && Setting.nostr_private_key.present?
+      res[:allows_nostr] = true
+      res[:nostrPubkey] = Setting.nostr_public_key
+    end
+
+    render json: res
   end
 
   # GET /.well-known/keysend/:username