Add keysend support for Lightning Address

Allow keysend payments to user addresses. Useful for Podcasting 2.0/v4v.

app/controllers/lnurlpay_controller.rb

@@ -1,4 +1,5 @@
 class LnurlpayController < ApplicationController
+  before_action :check_feature_enabled
   before_action :find_user_by_address
 
   MIN_SATS = 10
@@ -17,6 +18,20 @@ class LnurlpayController < ApplicationController
     }
   end
 
+  def keysend
+    http_status :not_found unless Setting.lndhub_keysend_enabled?
+
+    render json: {
+      status: "OK",
+      tag: "keysend",
+      pubkey: Setting.lndhub_public_key,
+      customData: [{
+        customKey: "696969",
+        customValue: @user.ln_account
+      }]
+    }
+  end
+
   def invoice
     amount = params[:amount].to_i / 1000 # msats
     address = params[:address]
@@ -72,4 +87,9 @@ class LnurlpayController < ApplicationController
     comment.length <= MAX_COMMENT_CHARS
   end
 
+  private
+
+  def check_feature_enabled
+    http_status :not_found if !Setting.lndhub_enabled?
+  end
 end