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

Conflicts:
- `README.md`:
  Upstream updated its README, while we have a completely different one.
  Kept our README.
- `app/controllers/concerns/web_app_controller_concern.rb`:
  Conflict because of glitch-soc's theming system.
  Additionally, glitch-soc has different behavior regarding moved accounts.
  Ported some of the changes, but kept our overall behavior.
- `app/javascript/packs/admin.js`:
  Code changes actually applied to `app/javascript/core/admin.js`

app/javascript/styles/mastodon/components.scss

@@ -4268,7 +4268,7 @@ a.status-card.compact:hover {
 }
 
 @keyframes heartbeat {
-  from {
+  0% {
     transform: scale(1);
     animation-timing-function: ease-out;
   }
@@ -7343,7 +7343,7 @@ noscript {
 
       path:first-child {
         fill: rgba($highlight-text-color, 0.25) !important;
-        fill-opacity: 100% !important;
+        fill-opacity: 1 !important;
       }
 
       path:last-child {