activitypub: note serializer: begrudgingly serialize quotes using misskey quoteUrl

app/serializers/activitypub/note_serializer.rb

@@ -9,7 +9,7 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
              :in_reply_to, :published, :url,
              :attributed_to, :to, :cc, :sensitive,
              :atom_uri, :in_reply_to_atom_uri,
-             :conversation
+             :conversation, :quote_url
 
   attribute :content
   attribute :content_map, if: :language?
@@ -149,6 +149,10 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
     end
   end
 
+  def quote_url
+    object.quote? ? ActivityPub::TagManager.instance.uri_for(object.quote) : nil
+  end
+
   def local?
     object.account.local?
   end