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/commission-structure.md

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+# Commission Structure
+
+## Overview
+
+The platform charges two types of commissions: marketplace commissions on product sales and rental commissions on property bookings.
+
+## Marketplace Commission
+
+- **Rate:** 5% of sale price (fixed, configured in PlatformConfig)
+- **Payer:** Seller
+- **Deduction:** Automatically deducted from seller payout
+- **Formula:**
+
+```
+Commission = Sale Price × 0.05
+Seller Payout = Sale Price - Commission
+```
+
+**Example:** Product sold for $100
+- Commission: $100 × 5% = $5.00
+- Seller receives: $95.00
+
+## Rental Commission
+
+- **Rate:** Variable, 5-10% based on landlord's subscription tier
+- **Payer:** Landlord
+- **Deduction:** Automatically deducted from landlord payout on booking completion
+
+| Tier | Commission Rate | Effective Savings vs BASIC |
+|------|----------------|--------------------------|
+| BASIC | 10% | - |
+| PRO | 7% | 30% less commission |
+| BUSINESS | 5% | 50% less commission |
+
+### Formula
+
+```
+Commission Amount = Booking Subtotal × (Tier Commission Rate / 100)
+Landlord Payout = Booking Subtotal - Commission Amount
+Total Charged to Tenant = Booking Subtotal + Deposit
+```
+
+### Calculation Flow
+
+1. Tenant creates booking request
+2. System looks up landlord's subscription tier
+3. Commission rate is determined from TIER_CONFIG
+4. Commission is calculated on subtotal (price × periods)
+5. On completion, payout is created: gross - commission = net
+
+### Example: $1,000 Monthly Booking
+
+| Component | BASIC (10%) | PRO (7%) | BUSINESS (5%) |
+|-----------|-------------|----------|---------------|
+| Subtotal | $1,000 | $1,000 | $1,000 |
+| Commission | $100 | $70 | $50 |
+| Landlord Payout | $900 | $930 | $950 |
+| Platform Revenue | $100 | $70 | $50 |
+
+## Deposit Handling
+
+- Deposits are separate from commission calculations
+- Deposits are fully returned on cancellation (regardless of refund policy)
+- Deposits are not subject to commission