fix: switch highlight to global store instead of URL params

URL param timing was unreliable with SvelteKit client-side routing.
Now CrossLink calls requestHighlight(id) setting a global variable
before goto(), and highlightFromUrl() reads it after data loads.
Double requestAnimationFrame ensures DOM has rendered after loaded=true.
Falls back to ?highlight= URL param for direct links.

frontend/src/lib/components/CrossLink.svelte

@@ -1,6 +1,7 @@
 <script lang="ts">
 	import { goto } from '$app/navigation';
 	import MdiIcon from './MdiIcon.svelte';
+	import { requestHighlight } from '$lib/highlight';
 
 	let {
 		href,
@@ -16,20 +17,17 @@
 		title?: string;
 	} = $props();
 
-	const targetHref = $derived(
-		entityId != null
-			? `${href.split('?')[0]}?highlight=${entityId}${href.includes('?') ? '&' + href.split('?')[1] : ''}`
-			: href
-	);
-
 	function navigate(e: MouseEvent) {
 		e.preventDefault();
 		e.stopPropagation();
-		goto(targetHref);
+		if (entityId != null) {
+			requestHighlight(entityId);
+		}
+		goto(href);
 	}
 </script>
 
-<a href={targetHref} class="crosslink" title={title || label} onclick={navigate}>
+<a {href} class="crosslink" title={title || label} onclick={navigate}>
 	<MdiIcon name={icon} size={12} />
 	<span>{label}</span>
 </a>