Add booking system with calendar and email notifications (v0.3.0)

- Booking Custom Post Type with full management features
- Room and guest relationship tracking
- Check-in/check-out date management with validation
- Booking status workflow (pending, confirmed, checked_in, checked_out, cancelled)
- Automatic price calculation using existing Calculator
- Availability system with real-time conflict detection
- AJAX endpoint for instant availability validation
- Calendar admin page with monthly view and room/building filters
- Color-coded booking status display with legend
- Email notifications for new bookings, confirmations, and cancellations
- HTML email templates with placeholder-based system
- Auto-generated booking references (BNB-YYYY-NNNNN)

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

PLAN.md

@@ -59,30 +59,30 @@ This document outlines the implementation plan for the WP BnB Management plugin.
 - [x] Price breakdown display
 - [x] Discount handling (via seasonal modifiers)
 
-## Phase 3: Booking System (v0.3.0)
+## Phase 3: Booking System (v0.3.0) - Complete
 
 ### Custom Post Type: Bookings
 
-- [ ] Guest reference
-- [ ] Room reference
-- [ ] Check-in/check-out dates
-- [ ] Status (pending, confirmed, checked-in, checked-out, cancelled)
-- [ ] Price calculation and storage
-- [ ] Notes field
+- [x] Guest reference
+- [x] Room reference
+- [x] Check-in/check-out dates
+- [x] Status (pending, confirmed, checked-in, checked-out, cancelled)
+- [x] Price calculation and storage
+- [x] Notes field
 
 ### Calendar Integration
 
-- [ ] Availability calendar per room
-- [ ] Availability calendar per building
-- [ ] Date range picker for bookings
-- [ ] Conflict detection
+- [x] Availability calendar per room
+- [x] Availability calendar per building
+- [x] Date range picker for bookings
+- [x] Conflict detection
 
 ### Booking Workflow
 
-- [ ] Booking creation (admin)
-- [ ] Status transitions
-- [ ] Email notifications
-- [ ] Booking confirmation
+- [x] Booking creation (admin)
+- [x] Status transitions
+- [x] Email notifications
+- [x] Booking confirmation
 
 ## Phase 4: Guest Management (v0.4.0)
 
@@ -290,7 +290,7 @@ The plugin will provide extensive hooks for customization:
 | 0.0.1   | Initial setup   | Complete |
 | 0.1.0   | Data structures | Complete |
 | 0.2.0   | Pricing         | Complete |
-| 0.3.0   | Bookings        | TBD      |
+| 0.3.0   | Bookings        | Complete |
 | 0.4.0   | Guests          | TBD      |
 | 0.5.0   | Services        | TBD      |
 | 0.6.0   | Frontend        | TBD      |