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>

docs/subscription-tiers.md

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+# Subscription Tier Comparison
+
+## Tier Overview
+
+| Feature | BASIC | PRO | BUSINESS |
+|---------|-------|-----|----------|
+| **Monthly Price** | Free | $9.99 | $29.99 |
+| **Max Active Listings** | 3 | 10 | Unlimited |
+| **Commission Rate** | 10% | 7% | 5% |
+| **Promo Discount** | None | 25% off | Free |
+| **Badge** | None | Priority | Verified |
+| **Advanced Analytics** | No | No | Yes |
+
+## Detailed Breakdown
+
+### BASIC (Free)
+- Best for: New landlords testing the platform
+- Up to 3 active rental listings
+- Standard 10% commission on bookings
+- No promotional discounts
+- No special badges
+- Basic dashboard access
+
+### PRO ($9.99/month)
+- Best for: Growing landlords with multiple properties
+- Up to 10 active rental listings
+- Reduced 7% commission (30% savings vs BASIC)
+- 25% discount on promoted listings
+- Priority badge on listings
+- Standard dashboard access
+
+### BUSINESS ($29.99/month)
+- Best for: Professional property managers
+- Unlimited active rental listings
+- Lowest 5% commission (50% savings vs BASIC)
+- Free promoted listings
+- Verified badge on listings
+- Advanced analytics dashboard
+
+## Break-Even Analysis
+
+### PRO Plan Break-Even
+At 7% commission instead of 10%, you save 3% per booking.
+Break-even monthly booking volume: $9.99 / 0.03 = **$333/month in bookings**
+
+### BUSINESS Plan Break-Even
+At 5% commission instead of 10%, you save 5% per booking.
+Break-even monthly booking volume: $29.99 / 0.05 = **$600/month in bookings**
+
+## Subscription Management
+- Plans can be changed at any time
+- Downgrades take effect immediately
+- Upgrades take effect immediately with a new 30-day billing period
+- Cancellation reverts to BASIC tier