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/models/form/admin_settings.rb

@@ -40,6 +40,9 @@ class Form::AdminSettings
     outgoing_spoilers
     require_invite_text
     captcha_enabled
+    media_cache_retention_period
+    content_cache_retention_period
+    backups_retention_period
   ).freeze
 
   BOOLEAN_KEYS = %i(
@@ -81,6 +84,7 @@ class Form::AdminSettings
   validates :bootstrap_timeline_accounts, existing_username: { multiple: true }
   validates :show_domain_blocks, inclusion: { in: %w(disabled users all) }
   validates :show_domain_blocks_rationale, inclusion: { in: %w(disabled users all) }
+  validates :media_cache_retention_period, :content_cache_retention_period, :backups_retention_period, numericality: { only_integer: true }, allow_blank: true
 
   def initialize(_attributes = {})
     super