feat(documents): inline relationship pills next to person names

Replaces the standalone "Beziehung" badge at the bottom of the
metadata drawer's Personen column with small inline pills attached
to each personCard — sender gets labelFromA, the single receiver
gets labelFromB. Matches docs/specs/stammbaum-doc-badge-spec.html.

Drops the now-unused RelationshipBadge component.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

frontend/src/lib/components/RelationshipPill.svelte

@@ -0,0 +1,10 @@
+<script lang="ts">
+type Props = { label: string };
+let { label }: Props = $props();
+</script>
+
+<span
+	class="inline-flex shrink-0 items-center rounded-full border border-accent bg-accent/25 px-2 py-px font-sans text-[10px] font-bold tracking-[0.07em] text-ink uppercase"
+>
+	{label}
+</span>