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/lib/projects.ts

@@ -32,6 +32,28 @@ export const projects = [
 	}
 ] as const;
 
+// The public /stats section: open data on the economy, energy and Gouda (src/routes/stats).
+export const statsPages = [
+	{
+		name: 'economy',
+		subtitle: 'rates, inflation, bond spreads, GDP and debt',
+		href: '/stats/economy',
+		external: false
+	},
+	{
+		name: 'energy',
+		subtitle: 'tariffs, oil and gas, renewables, heat pumps and EVs',
+		href: '/stats/energy',
+		external: false
+	},
+	{
+		name: 'gouda',
+		subtitle: 'population, housing and neighbourhoods in Gouda',
+		href: '/stats/gouda',
+		external: false
+	}
+] as const;
+
 type Tracker = {
 	name: string;
 	subtitle: string;