UX: Indicate that "Show replies" button does not work for deleted posts (#16304)

app/assets/javascripts/discourse/app/widgets/post-menu.js

@@ -268,6 +268,7 @@ registerButton("replies", (attrs, state, siteSettings) => {
     labelOptions: { count: replyCount },
     label: attrs.mobileView ? "post.has_replies_count" : "post.has_replies",
     iconRight: !siteSettings.enable_filtered_replies_view || attrs.mobileView,
+    disabled: !!attrs.deleted,
   };
 });
 

app/assets/stylesheets/common/base/topic-post.scss

@@ -388,6 +388,10 @@ nav.post-controls {
           color: currentColor;
         }
       }
+      &[disabled]:hover {
+        background-color: transparent;
+        cursor: not-allowed;
+      }
       &.fade-out {
         opacity: 1;
       }