style: standardise link hover underline (2px, offset-4, accent) globally

Move text-decoration-thickness/underline-offset into the global a:hover
base rule so every link that shows an underline on hover gets identical
treatment: 2px thick, 4px offset, accent colour.

Remove the now-redundant per-component decoration-brand-mint / decoration-
accent / decoration-2 / underline-offset-{2,4} utilities from DocumentList,
enrich, persons, PersonDocumentList, and PanelMetadata.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

frontend/src/routes/persons/+page.svelte

@@ -119,9 +119,7 @@ function handleSearch() {
 
 						<!-- Info -->
 						<div class="min-w-0 flex-1">
-							<p
-								class="truncate font-serif text-base font-medium text-ink decoration-brand-mint decoration-2 underline-offset-2 group-hover:underline"
-							>
+							<p class="truncate font-serif text-base font-medium text-ink group-hover:underline">
 								{person.firstName}
 								{person.lastName}
 							</p>

frontend/src/routes/persons/[id]/PersonDocumentList.svelte

@@ -86,7 +86,7 @@ const visibleDocuments = $derived(
 								</div>
 								<div class="min-w-0">
 									<div
-										class="truncate font-serif text-base font-medium text-ink decoration-brand-mint decoration-2 underline-offset-2 group-hover:underline"
+										class="truncate font-serif text-base font-medium text-ink group-hover:underline"
 									>
 										{doc.title || doc.originalFilename}
 									</div>