UX: Onebox container sizing (#25658)

* UX: scope onebox container size to not images

* UX: increase max-width for onebox img

plugins/chat/assets/stylesheets/common/chat-message-images.scss

@@ -18,7 +18,9 @@ $max_image_height: 150px;
   }
 
   .onebox {
-    container-type: inline-size;
+    &:not(img) {
+      container-type: inline-size;
+    }
 
     .thumbnail {
       &.onebox-avatar {
@@ -29,6 +31,10 @@ $max_image_height: 150px;
       }
     }
 
+    .onebox-body .aspect-image {
+      max-width: 50%;
+    }
+
     @container (width < 400px) {
       .onebox-body {
         display: flex;