fix: keep the unread comment icon's weight out of the forced style

The discussion list signals unread replies by icon weight alone: a
solid comment for unread against a regular one for read. Forcing a
FontAwesome style restyled both to the same weight, making the two
states indistinguishable.

The unread icon now opts out with noStyleOverride, the same exemption
the online indicator and subscription stars use (#4873). The read-state
icon still follows the forced style, so the contrast survives — the
checkmark shown on hover is an action glyph, not a weight signal, and
keeps following the forced style too.

Author: imorland

framework/core/js/src/forum/components/DiscussionListItem.tsx

@@ -319,7 +319,15 @@ export default class DiscussionListItem<CustomAttrs extends IDiscussionListItemA
     return (
       <DiscussionListItemStatsItem
         className="DiscussionListItem-count"
-        icon={showUnread ? [<Icon name={'fas fa-check _checkmark'} />, <Icon name={'fas fa-comment _comment'} />] : <Icon name={'far fa-comment'} />}
+        icon={
+          showUnread ? (
+            // The solid comment against the read state's regular one is what
+            // signals unread, so it must keep its weight under a forced style.
+            [<Icon name={'fas fa-check _checkmark'} />, <Icon name={'fa-solid fa-comment _comment'} noStyleOverride />]
+          ) : (
+            <Icon name={'far fa-comment'} />
+          )
+        }
         label={showUnread ? abbreviateNumber(discussion.unreadCount()) : abbreviateNumber(discussion.replyCount())}
         ariaLabel={app.translator.trans(a11yKey, { count: discussion.unreadCount() })}
         onclick={showUnread ? this.markAsRead.bind(this) : undefined}