feat(stammbaum): person detail Beziehungen card

- persons/[id]/+page.server.ts loads relationships and
  inferred-relationships in the existing parallel fetch.
- New PersonRelationshipsCard renders direct chips (mint) and the
  top-5 derived chips (grey) on /persons/{id}, both linked to the
  other person's page. Empty state shows
  "Noch keine Beziehungen bekannt." in muted serif.
- Card sits in the right column above the document lists.

Refs #358.

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

frontend/src/routes/persons/[id]/+page.svelte

@@ -6,6 +6,7 @@ import PersonCard from './PersonCard.svelte';
 import NameHistoryCard from './NameHistoryCard.svelte';
 import CoCorrespondentsList from './CoCorrespondentsList.svelte';
 import PersonDocumentList from './PersonDocumentList.svelte';
+import PersonRelationshipsCard from './PersonRelationshipsCard.svelte';
 
 let { data } = $props();
 
@@ -64,10 +65,18 @@ const coCorrespondents = $derived.by(() => {
 			</div>
 		</div>
 
-		<!-- Right column: correspondents + documents -->
+		<!-- Right column: correspondents + relationships + documents -->
 		<div>
 			<CoCorrespondentsList coCorrespondents={coCorrespondents} personId={person.id} />
 
+			<div class="mt-6">
+				<PersonRelationshipsCard
+					personId={person.id}
+					relationships={data.relationships}
+					inferredRelationships={data.inferredRelationships}
+				/>
+			</div>
+
 			<PersonDocumentList
 				documents={sentDocuments}
 				heading={m.person_docs_heading()}