quickshell: fix worm never appearing (var array reassign emits no notify)

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

settings/quickshell.nix

@@ -872,7 +872,12 @@ in
                         let t = worm.trail;
                         t.unshift(Qt.point(nx, ny));
                         if (t.length > weird.segments * weird.lag) t.pop();
-                        worm.trail = t;   // reassign: arrays don't notify on mutation
+                        // slice(), not `t`: a var property assigned the array
+                        // it already holds emits no change signal, so the
+                        // segments would bind once to an empty trail and never
+                        // hear about a single tick. Copy = new reference =
+                        // notification. 30 short arrays a second is nothing.
+                        worm.trail = t.slice();
                     }
                 }