Merge branch 'master' into glitch-soc/merge-upstream

Conflicts:
- `.env.production.sample`:
  Upstream deleted it, I decided to keep it.
- `package.json`:
  Upstream updated a dependency textually too close to wavesurfer.js
  which has been deleted from upstream but is kept in glitch-soc for now.

app/serializers/activitypub/note_serializer.rb

@@ -172,6 +172,8 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
     attributes :type, :media_type, :url, :name, :blurhash
     attribute :focal_point, if: :focal_point?
 
+    has_one :icon, serializer: ActivityPub::ImageSerializer, if: :thumbnail?
+
     def type
       'Document'
     end
@@ -195,6 +197,14 @@ class ActivityPub::NoteSerializer < ActivityPub::Serializer
     def focal_point
       [object.file.meta['focus']['x'], object.file.meta['focus']['y']]
     end
+
+    def icon
+      object.thumbnail
+    end
+
+    def thumbnail?
+      object.thumbnail.present?
+    end
   end
 
   class MentionSerializer < ActivityPub::Serializer