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

Conflicts:
- `.github/workflows/build-image.yml`:
  Fix erroneous deletion in a previous merge.
- `Gemfile`:
  Conflict caused by glitch-soc-only hCaptcha dependency
- `app/controllers/auth/sessions_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
- `app/controllers/filters_controller.rb`:
  Minor conflict due to glitch-soc's theming system.
- `app/serializers/rest/status_serializer.rb`:
  Minor conflict due to glitch-soc having an extra `local_only` property

app/helpers/routing_helper.rb

@@ -16,7 +16,11 @@ module RoutingHelper
   def full_asset_url(source, **options)
     source = ActionController::Base.helpers.asset_url(source, **options) unless use_storage?
 
-    URI.join(root_url, source).to_s
+    URI.join(asset_host, source).to_s
+  end
+
+  def asset_host
+    Rails.configuration.action_controller.asset_host || root_url
   end
 
   def full_pack_url(source, **options)