Add schedule preview dropdown styles and various improvements

- Add .schedule-preview-dropdown and .schedule-preview-item CSS classes
- Add .btn-schedule-preview badge styling
- Add preview functionality for entity list views
- Improve modal and dropdown styling
- Various JS and SCSS enhancements

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

sources/scss/components/_combinations.scss

@@ -3,6 +3,7 @@
  * Product attribute combination selection styles
  */
 
+@use "sass:color";
 @use '../variables' as *;
 @use '../mixins' as *;
 
@@ -298,7 +299,7 @@
 
             &:hover {
                 background: $es-primary-hover;
-                border-color: darken($es-primary-hover, 5%);
+                border-color: color.adjust($es-primary-hover, $lightness: -5%);
             }
         }
     }