fix(web): dark-mode variants for discovery empty-queue card

web/src/routes/admin/discovery/+page.svelte

@@ -94,7 +94,9 @@
 	</p>
 
 	{#if queue.length === 0}
-		<p class="mt-8 rounded border border-stone-200 bg-stone-50 p-6 text-center text-stone-600">
+		<p
+			class="mt-8 rounded border border-stone-200 bg-stone-50 p-6 text-center text-stone-600 dark:border-stone-700 dark:bg-stone-900 dark:text-stone-400"
+		>
 			Keine Einträge in der Warteschlange.
 		</p>
 	{:else}