feat: card highlight system for cross-entity navigation

When clicking a CrossLink, the target entity ID is passed as
?highlight=<id> in the URL. The destination page:
1. Shows a semi-transparent dim overlay (z-index: 10)
2. Finds the card with data-entity-id matching the ID
3. Scrolls to it smoothly (block: center)
4. Applies a pulsing primary-color box-shadow animation (z-index: 11)
5. Cleans up overlay + animation after 2 seconds

If the card isn't in DOM yet (data still loading), a MutationObserver
waits up to 5 seconds for it to appear.

Changes:
- New highlight.ts utility with highlightFromUrl(), MutationObserver,
  dim overlay management
- Card component accepts entityId prop → data-entity-id attribute
- CrossLink accepts entityId prop → appends ?highlight=<id> to href
- All 9 entity pages: Card elements have entityId, highlightFromUrl()
  called after data loads
- CSS: cardHighlight keyframe animation + nav-dim-overlay styles

frontend/src/lib/components/CrossLink.svelte

@@ -6,22 +6,30 @@
 		href,
 		icon = 'mdiLink',
 		label,
+		entityId = null,
 		title = '',
 	}: {
 		href: string;
 		icon?: string;
 		label: string;
+		entityId?: number | string | null;
 		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(href);
+		goto(targetHref);
 	}
 </script>
 
-<a {href} class="crosslink" title={title || label} onclick={navigate}>
+<a href={targetHref} class="crosslink" title={title || label} onclick={navigate}>
 	<MdiIcon name={icon} size={12} />
 	<span>{label}</span>
 </a>