Re-add description_hash

Necessary for lnurlpay-enabled wallets

app/controllers/lnurlpay_controller.rb

@@ -37,7 +37,8 @@ class LnurlpayController < ApplicationController
 
     payment_request = @user.ln_create_invoice({
       amount: amount, # we create invoices in sats
-      memo: memo
+      memo: memo,
+      description_hash: Digest::SHA2.hexdigest(metadata(address)),
     })
 
     render json: {

app/services/lndhub.rb

@@ -49,7 +49,8 @@ class Lndhub
   def addinvoice(payload)
     invoice = post "addinvoice", {
       amt: payload[:amount],
-      memo: payload[:memo]
+      memo: payload[:memo],
+      description_hash: payload[:description_hash]
     }
 
     invoice["payment_request"]