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]/PersonRelationshipsCard.svelte

@@ -0,0 +1,100 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+import { inferredRelationshipLabel } from '$lib/relationshipLabels';
+import type { components } from '$lib/generated/api';
+
+type RelationshipDTO = components['schemas']['RelationshipDTO'];
+type InferredRelationshipWithPersonDTO = components['schemas']['InferredRelationshipWithPersonDTO'];
+
+interface Props {
+	personId: string;
+	relationships: RelationshipDTO[];
+	inferredRelationships: InferredRelationshipWithPersonDTO[];
+}
+
+let { personId, relationships, inferredRelationships }: Props = $props();
+
+const topDerived = $derived(inferredRelationships.slice(0, 5));
+
+function chipLabel(rel: RelationshipDTO): string {
+	const viewpointIsSubject = rel.personId === personId;
+	switch (rel.relationType) {
+		case 'PARENT_OF':
+			return viewpointIsSubject ? m.relation_parent_of() : m.relation_child_of();
+		case 'SPOUSE_OF':
+			return m.relation_spouse_of();
+		case 'SIBLING_OF':
+			return m.relation_sibling_of();
+		case 'FRIEND':
+			return m.relation_friend();
+		case 'COLLEAGUE':
+			return m.relation_colleague();
+		case 'EMPLOYER':
+			return m.relation_employer();
+		case 'DOCTOR':
+			return m.relation_doctor();
+		case 'NEIGHBOR':
+			return m.relation_neighbor();
+		default:
+			return m.relation_other();
+	}
+}
+
+function otherId(rel: RelationshipDTO): string {
+	return rel.personId === personId ? rel.relatedPersonId : rel.personId;
+}
+
+function otherName(rel: RelationshipDTO): string {
+	return rel.personId === personId ? rel.relatedPersonDisplayName : rel.personDisplayName;
+}
+</script>
+
+<div class="rounded-sm border border-line bg-surface p-6 shadow-sm">
+	<h2 class="mb-5 text-xs font-bold tracking-widest text-ink-3 uppercase">
+		{m.person_relationships_heading()}
+	</h2>
+
+	{#if relationships.length === 0 && topDerived.length === 0}
+		<p class="font-serif text-sm text-ink-2 italic">{m.person_relationships_empty()}</p>
+	{:else}
+		{#if relationships.length > 0}
+			<ul class="mb-4 space-y-2">
+				{#each relationships as rel (rel.id)}
+					<li class="flex items-center gap-2">
+						<span
+							class="inline-flex shrink-0 items-center rounded-full border border-accent/40 bg-accent/15 px-2 py-0.5 font-sans text-[10px] font-bold tracking-widest text-ink uppercase"
+						>
+							{chipLabel(rel)}
+						</span>
+						<a
+							href="/persons/{otherId(rel)}"
+							class="min-w-0 flex-1 truncate font-serif text-sm text-ink hover:underline"
+						>
+							{otherName(rel)}
+						</a>
+					</li>
+				{/each}
+			</ul>
+		{/if}
+
+		{#if topDerived.length > 0}
+			<ul class="space-y-2">
+				{#each topDerived as derived (derived.person.id)}
+					<li class="flex items-center gap-2">
+						<span
+							class="inline-flex shrink-0 items-center rounded-full border border-line bg-muted/50 px-2 py-0.5 font-sans text-[10px] font-bold tracking-widest text-ink-2 uppercase"
+						>
+							{inferredRelationshipLabel(derived.label)}
+						</span>
+						<a
+							href="/persons/{derived.person.id}"
+							class="min-w-0 flex-1 truncate font-serif text-sm text-ink-2 hover:underline"
+						>
+							{derived.person.displayName}
+						</a>
+					</li>
+				{/each}
+			</ul>
+		{/if}
+	{/if}
+</div>