Add warning for sensitive audio posts (#17885)

app/javascript/styles/mastodon/components.scss

@@ -5939,6 +5939,13 @@ a.status-card.compact:hover {
     height: 100%;
   }
 
+  &.inactive {
+    audio,
+    .video-player__controls {
+      visibility: hidden;
+    }
+  }
+
   .video-player__volume::before,
   .video-player__seek::before {
     background: currentColor;