Add featured tag add/remove activity handler (#19408)

app/lib/activitypub/activity/add.rb

@@ -2,12 +2,32 @@
 
 class ActivityPub::Activity::Add < ActivityPub::Activity
   def perform
-    return unless @json['target'].present? && value_or_id(@json['target']) == @account.featured_collection_url
+    return if @json['target'].blank?
 
+    case value_or_id(@json['target'])
+    when @account.featured_collection_url
+      case @object['type']
+      when 'Hashtag'
+        add_featured_tags
+      else
+        add_featured
+      end
+    end
+  end
+
+  private
+
+  def add_featured
     status = status_from_object
 
     return unless !status.nil? && status.account_id == @account.id && !@account.pinned?(status)
 
     StatusPin.create!(account: @account, status: status)
   end
+
+  def add_featured_tags
+    name = @object['name']&.delete_prefix('#')
+
+    FeaturedTag.create!(account: @account, name: name) if name.present?
+  end
 end