FIX: overflow of channel title in preview card (#21112)

plugins/chat/assets/stylesheets/common/chat-channel-title.scss

@@ -1,3 +1,4 @@
+//appears in: header of chat pane, channel info, preview card
 .chat-channel-title-wrapper {
   display: flex;
   align-items: center;
@@ -9,6 +10,10 @@
   align-items: center;
   @include ellipsis;
 
+  .chat-channel-preview-card & {
+    max-width: 100%;
+  }
+
   &__user-info {
     overflow: hidden;
   }