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

Conflicts:
- `app/controllers/home_controller.rb`:
  Upstream made it so `/web` is available to non-logged-in users
  and `/` redirects to `/web` instead of `/about`.
  Kept our version since glitch-soc's WebUI doesn't have what's
  needed yet and I think /about is still a much better landing
  page anyway.
- `app/models/form/admin_settings.rb`:
  Upstream added new settings, and glitch-soc had an extra setting.
  Not really a conflict.
  Added upstream's new settings.
- `app/serializers/initial_state_serializer.rb`:
  Upstream added a new `server` initial state object.
  Not really a conflict.
  Merged upstream's changes.
- `app/views/admin/settings/edit.html.haml`:
  Upstream added new settings.
  Not really a conflict.
  Merged upstream's changes.
- `app/workers/scheduler/feed_cleanup_scheduler.rb`:
  Upstream refactored that part and removed the file.
  Ported our relevant changes into `app/lib/vacuum/feeds_vacuum.rb`
- `config/settings.yml`:
  Upstream added new settings.
  Not a real conflict.
  Added upstream's new settings.

app/serializers/activitypub/public_key_serializer.rb

@@ -6,7 +6,7 @@ class ActivityPub::PublicKeySerializer < ActivityPub::Serializer
   attributes :id, :owner, :public_key_pem
 
   def id
-    [ActivityPub::TagManager.instance.uri_for(object), '#main-key'].join
+    ActivityPub::TagManager.instance.key_uri_for(object)
   end
 
   def owner