style: enhance checkbox appearance in Card component

- Increase checkbox size to 24x24px
- Add rounded corners
- Implement visible border with theme color
- Add smooth transition animation
- Improve checked state visibility

src/lib/components/Card.svelte

@@ -24,7 +24,7 @@
 				name=""
 				id="card-{cardData.id}"
 				onchange={toggleCardChecked}
-				class="appearance-none"
+				class="appearance-none h-6 w-6 rounded-lg border-2 border-primary-FestiveRed-dark checked:bg-primary-FestiveRed-dark checked:border-primary-FestiveRed-dark cursor-pointer transition-all duration-200 ease-in-out"
 			/>
 		</div>
 		<div>