feat(abgabe): Reservierungs-/Abgabe-Status (verfügbar/reserviert/abgegeben)

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

gerbil-manager-web/src/components/AppShell.tsx

@@ -24,6 +24,8 @@ const SECONDARY: NavItem[] = [
   { to: '/gehege', label: de.nav.enclosures, icon: '🏜️' },
   { to: '/kontakte', label: de.nav.contacts, icon: '📇' },
   { to: '/abgabe', label: de.nav.forSale, icon: '🏡' },
+  // ABGABE-STATUS: Reservierungs-/Abgabe-Status
+  { to: '/reservierungen', label: de.nav.reservations, icon: '🔖' },
   // INBOX-1: Anfragen-Posteingang
   { to: '/anfragen', label: de.nav.requests, icon: '📨' },
   { to: '/statistik', label: de.nav.statistics, icon: '📊' },