Add WooCommerce integration for payments, invoices, and order management (v0.11.0)

- Product sync: Virtual WC products for rooms with bidirectional linking
- Cart/Checkout: Booking data in cart items, availability validation, dynamic pricing
- Orders: Automatic booking creation on payment, status mapping, guest record creation
- Invoices: PDF generation via mPDF, auto-attach to emails, configurable numbering
- Refunds: Full refund cancels booking, partial refund records amount only
- Admin: Cross-linked columns and row actions between bookings and orders
- Settings: WooCommerce tab with subtabs (General, Products, Orders, Invoices)
- HPOS compatibility declared for High-Performance Order Storage

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

PLAN.md

@@ -204,12 +204,12 @@ This document outlines the implementation plan for the WP BnB Management plugin.
 - [x] Transient-based rate limiting with tiered limits
 - [x] API settings tab with enable/disable toggles
 
-### Phase 11: WooCommerce Integration (v0.11.0)
+### Phase 11: WooCommerce Integration (v0.11.0) - Complete
 
-- [ ] Payment processing
-- [ ] Invoice generation
-- [ ] Order management
-- [ ] Refund handling
+- [x] Payment processing
+- [x] Invoice generation
+- [x] Order management
+- [x] Refund handling
 
 ## Phase 12: Security Audit (v0.12.0)
 
@@ -359,6 +359,6 @@ The plugin will provide extensive hooks for customization:
 | 0.8.0   | Dashboard               | Complete |
 | 0.9.0   | Prometheus Metrics      | Complete |
 | 0.10.0  | API Endpoints           | Complete |
-| 0.11.0  | WooCommerce Integration | TBD      |
+| 0.11.0  | WooCommerce Integration | Complete |
 | 0.12.0  | Security Audit          | TBD      |
 | 1.0.0   | Stable Release          | TBD      |