Herstructureer src/ naar feature-based folderstructuur

Volgt de aanpak uit het React 2025 folder structure artikel en het
SlpModularCms/frontend referentieproject: components/{layout,ui,shared},
features/landing/{components,data,hooks,pages,__tests__}, en lib/ voor
de query client. routes/index.tsx wordt een dunne wrapper rond de nieuwe
features/landing/pages/LandingPage.tsx.

src/features/landing/hooks/usePackagesQuery.ts

@@ -0,0 +1,19 @@
+import { useQuery } from '@tanstack/react-query';
+import { packages, type PackageCardData } from '../data/content';
+
+/**
+ * Placeholder query hook (requirements FR-5). The queryFn currently just resolves the
+ * static package data, wrapped in a Promise so the calling component already consumes
+ * it exactly the way it will once a real API exists — only this queryFn's body will
+ * need to change in a future iteration.
+ */
+async function fetchPackages(): Promise<PackageCardData[]> {
+  return Promise.resolve(packages);
+}
+
+export function usePackagesQuery() {
+  return useQuery({
+    queryKey: ['packages'],
+    queryFn: fetchPackages,
+  });
+}