Add frontend features with search, shortcodes, widgets, and blocks (v0.6.0)

- Room search with availability, capacity, room type, amenity, price range, and building filters
- AJAX-powered search with pagination and load more
- Shortcodes: [bnb_buildings], [bnb_rooms], [bnb_room_search], [bnb_building], [bnb_room]
- Widgets: Similar Rooms, Building Rooms, Availability Calendar
- Gutenberg blocks: Building, Room, Room Search, Buildings List, Rooms List
- Frontend CSS with responsive design and CSS custom properties
- Frontend JavaScript with SearchForm, CalendarWidget, AvailabilityForm, PriceCalculator

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

wp-bnb.php

@@ -3,7 +3,7 @@
  * Plugin Name: WP BnB Management
  * Plugin URI: https://src.bundespruefstelle.ch/magdev/wp-bnb
  * Description: A comprehensive Bed & Breakfast management system for WordPress. Manage buildings, rooms, bookings, and guests.
- * Version: 0.5.0
+ * Version: 0.6.0
  * Requires at least: 6.0
  * Requires PHP: 8.3
  * Author: Marco Graetsch
@@ -24,7 +24,7 @@ if ( ! defined( 'ABSPATH' ) ) {
 }
 
 // Plugin version constant - MUST match Version in header above.
-define( 'WP_BNB_VERSION', '0.5.0' );
+define( 'WP_BNB_VERSION', '0.6.0' );
 
 // Plugin path constants.
 define( 'WP_BNB_PATH', plugin_dir_path( __FILE__ ) );