feat(persons): enrich /persons list with stats bar, life dates, doc count chip

Load /api/stats in parallel; PersonsStatsBar shows totals; person cards
show alias, life date range, and document count badge.

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

frontend/src/routes/persons/PersonsEmptyState.svelte

@@ -0,0 +1,18 @@
+<script lang="ts">
+import { m } from '$lib/paraglide/messages.js';
+</script>
+
+<div
+	class="flex flex-col items-center justify-center rounded-lg border border-dashed border-line bg-surface py-16 text-center"
+>
+	<div class="mb-3 flex h-12 w-12 items-center justify-center rounded-full bg-muted text-ink">
+		<img
+			src="/degruyter-icons/Simple/Medium-24px/SVG/Action/Account-MD.svg"
+			alt=""
+			aria-hidden="true"
+			class="h-6 w-6"
+		/>
+	</div>
+	<p class="font-serif text-lg text-ink">{m.persons_empty_heading()}</p>
+	<p class="mt-1 font-sans text-sm text-ink-2">{m.persons_empty_text()}</p>
+</div>