stats: /stats overview, economy, energy and Gouda pages; CBS series map; nav, homepage, /start and sitemap links

- CBS_SERIES: CPI, household tariffs (2007-now), energy balance, renewables, heat pumps,
  solar, cars, population (monthly, since 1942, components), house prices, housing stock,
  municipal levies for Gouda and its neighbours
- shared StatChart/Kpi/chart helpers with per-chart source attribution
- drop Eurostat nrg_pc_20x_h (404; CBS covers that history)

src/routes/+page.svelte

@@ -4,7 +4,7 @@
 	import ProgressBar from '#lib/components/ProgressBar.svelte';
 	import ListeningCard from '#lib/music/ListeningCard.svelte';
 	import CatalogGrid from '#lib/components/CatalogGrid.svelte';
-	import { projects, visibleTrackers } from '#lib/projects.js';
+	import { projects, statsPages, visibleTrackers } from '#lib/projects.js';
 	import ArrowRight from 'lucide-svelte/icons/arrow-right';
 	import ExternalLink from 'lucide-svelte/icons/external-link';
 	import Mail from 'lucide-svelte/icons/mail';
@@ -144,6 +144,17 @@
 		/>
 	</section>
 
+	<section aria-labelledby="stats-heading" class="border-t border-[var(--site-border)] pt-8">
+		<h2 id="stats-heading" class="mb-4 text-2xl font-semibold tracking-tight">
+			<a
+				href={resolve('/stats')}
+				class="inline-flex items-center gap-1 hover:text-[var(--site-muted)]"
+				>stats <ArrowRight size={20} aria-hidden="true" /></a
+			>
+		</h2>
+		<CatalogGrid items={statsPages} subtitleClass="mt-1 block text-base text-[var(--site-muted)]" />
+	</section>
+
 	<section aria-labelledby="lists-heading" class="pt-14 sm:pt-20">
 		<h2 id="lists-heading" class="mb-4 text-2xl font-semibold tracking-tight">
 			<a