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

Conflicts:
- `README.md`:
  Upstream changed their README, we have our own.
  Kept ours.
- `app/helpers/application_helper.rb`:
  Minor code style fix upstream, on a line that is different in glitch-soc
  due to the different theming system.
  Applied the code style fix to our own code.
- `app/views/settings/preferences/appearance/show.html.haml`:
  Code style fix on a line next to lines exclusive to glitch-soc.
  Applied upstream changes.
- `yarn.lock`:
  Upstream updated a dependency textually close to a glitch-soc-only
  dependency.
  Updated the dependency like upstream did.

app/services/translate_status_service.rb

@@ -6,19 +6,29 @@ class TranslateStatusService < BaseService
   include FormattingHelper
 
   def call(status, target_language)
-    raise Mastodon::NotPermittedError unless status.translatable?
-
     @status = status
     @content = status_content_format(@status)
     @target_language = target_language
 
+    raise Mastodon::NotPermittedError unless permitted?
+
     Rails.cache.fetch("translations/#{@status.language}/#{@target_language}/#{content_hash}", expires_in: CACHE_TTL) { translation_backend.translate(@content, @status.language, @target_language) }
   end
 
   private
 
   def translation_backend
-    TranslationService.configured
+    @translation_backend ||= TranslationService.configured
+  end
+
+  def permitted?
+    return false unless @status.distributable? && @status.content.present? && TranslationService.configured?
+
+    languages[@status.language]&.include?(@target_language)
+  end
+
+  def languages
+    Rails.cache.fetch('translation_service/languages', expires_in: 7.days, race_condition_ttl: 1.hour) { TranslationService.configured.languages }
   end
 
   def content_hash