Toast fixes

ui/src/styles.css

@@ -198,6 +198,21 @@
   animation: panel-fade-in 0.18s ease-out;
 }
 
+/* Toast auto-dismiss countdown; duration set inline per toast. */
+@keyframes toast-countdown {
+  to {
+    transform: scaleX(0);
+  }
+}
+.toast-countdown {
+  animation: toast-countdown linear forwards;
+}
+/* unlayered on purpose: a Tailwind group-hover utility would lose to the
+   unlayered animation shorthand above */
+.group:hover > .toast-countdown {
+  animation-play-state: paused;
+}
+
 /* Accent tone (data-accent set by SettingsService; absent = graphite/zinc).
    Each tone is one hue+chroma line; the formula blocks below derive --primary,
    --ring and the cursor-row tint for light and both dark states. The dark