refactoring: magic strings and tests for Vorgang overview page

src/routes/(angemeldet)/list/+page.svelte

@@ -2,6 +2,7 @@
 	import Trash from '$lib/icons/Trash.svelte';
 	import Folder from '$lib/icons/Folder.svelte';
 	import EmptyList from '$lib/components/EmptyList.svelte';
+	import { ROUTE_NAMES } from '../../index.js';
 
 	let { data } = $props();
 
@@ -49,7 +50,7 @@
 				{#each vorgangList as vorgangItem}
 					<li data-testid="test-list-item">
 						<a
-							href="/list/{vorgangItem.vorgangToken}?pin={vorgangItem.vorgangPIN}"
+							href="{ROUTE_NAMES.VORGANG(vorgangItem.vorgangToken, vorgangItem.vorgangPIN)}"
 							class="flex justify-between gap-x-6 py-5"
 						>
 							<div class="flex gap-x-4">