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

Conflicts:
- `README.md`:
  Our README is completely different. Discarded upstream changes.
- `app/javascript/packs/mailer.js`:
  We had removed the file. Move the changes to `app/javascript/core/mailer.js`.

app/views/layouts/embedded.html.haml

@@ -24,5 +24,5 @@
   %body.embed
     = yield
 
-    .logo-resources
-      = raw render file: Rails.root.join('app', 'javascript', 'images', 'logo_transparent.svg')
+    .logo-resources{ 'tabindex' => '-1', 'inert' => true, 'aria-hidden' => true }
+      = render_symbol :icon