feat: subscription tiers, period filter, dashboards, docs

- Add subscription tiers (Basic/Pro/Business) with listing limits and dynamic commission
- Add daily/monthly period filter on rentals page
- Add landlord dashboard with earnings chart, stat cards, property performance
- Add landlord subscription management page
- Add tenant dashboard with upcoming stays
- Add business model documentation

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

client/src/components/layout/LandlordLayout.tsx

@@ -1,5 +1,5 @@
 import { NavLink, Outlet } from 'react-router-dom';
-import { LayoutDashboard, List, Calendar, CalendarDays, DollarSign, Star } from 'lucide-react';
+import { LayoutDashboard, List, Calendar, CalendarDays, DollarSign, Star, CreditCard } from 'lucide-react';
 
 const navItems = [
   { to: '/landlord', icon: LayoutDashboard, label: 'Dashboard', end: true },
@@ -8,6 +8,7 @@ const navItems = [
   { to: '/landlord/calendar', icon: CalendarDays, label: 'Calendar' },
   { to: '/landlord/payouts', icon: DollarSign, label: 'Payouts' },
   { to: '/landlord/reviews', icon: Star, label: 'Reviews' },
+  { to: '/landlord/subscription', icon: CreditCard, label: 'Subscription' },
 ];
 
 export function LandlordLayout() {