style(select): improve select item hover and active state visual hierarchy

- Use --bg-hover for hover state (more visible)
- Add font-weight: 500 to active/selected state for better distinction

web/src/index.css

@@ -426,12 +426,13 @@ pre,
 }
 
 .ui-select-item:hover:not(:disabled) {
-  background: var(--bg-tertiary);
+  background: var(--bg-hover);
 }
 
 .ui-select-item.is-active {
   background: var(--bg-selected);
   color: var(--text-primary);
+  font-weight: 500;
 }
 
 .ui-select-item:disabled {