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>

CHANGELOG.md

@@ -5,6 +5,74 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## [0.6.0] - 2026-02-02
+
+### Added
+
+- Frontend Features System:
+  - Room search with multiple filters (availability, capacity, room type, amenities, price range, building)
+  - AJAX-powered search with pagination and "Load More" functionality
+  - Date validation (check-out after check-in, minimum today)
+  - Real-time availability checking on single room pages
+  - Price calculator with breakdown display
+- Shortcodes:
+  - `[bnb_buildings]` - Display buildings list/grid with filtering and sorting
+  - `[bnb_rooms]` - Display rooms list/grid with multiple filter options
+  - `[bnb_room_search]` - Interactive room search form with results
+  - `[bnb_building id="X"]` - Display single building details
+  - `[bnb_room id="X"]` - Display single room details with availability form
+- WordPress Widgets:
+  - Similar Rooms widget (shows rooms from same building/type)
+  - Building Rooms widget (lists all rooms in a building)
+  - Availability Calendar widget (mini calendar with booking status)
+- Gutenberg Blocks:
+  - Building block with ID selector
+  - Room block with ID selector
+  - Room Search block with filter presets
+  - Buildings List block with layout options
+  - Rooms List block with filter options
+  - Server-side rendered blocks for consistent output
+- Frontend Search Class (`src/Frontend/Search.php`):
+  - Core search functionality with availability filtering
+  - Price range filtering with Calculator integration
+  - Pagination support
+  - AJAX endpoints: search_rooms, get_availability, get_calendar, calculate_price
+  - Room data formatting for JSON responses
+- Frontend Shortcodes Class (`src/Frontend/Shortcodes.php`):
+  - All shortcode registration and handlers
+  - Grid/list layout support
+  - Column configuration (1-4 columns)
+  - Sorting options (title, date, price, capacity)
+  - Limit and offset support
+- Block Registrar Class (`src/Blocks/BlockRegistrar.php`):
+  - Gutenberg block registration
+  - Block editor assets (CSS/JS)
+  - Server-side render callbacks
+  - Block data localization for editor
+- Frontend Assets:
+  - Comprehensive CSS with CSS custom properties for theming
+  - Building and room card styles
+  - Search form and results styling
+  - Calendar widget styling with availability states
+  - Responsive design (breakpoints: 480px, 768px, 1024px)
+  - JavaScript with SearchForm, CalendarWidget, AvailabilityForm, PriceCalculator classes
+  - AJAX integration with proper error handling
+  - XSS-safe DOM construction (no innerHTML with user data)
+
+### Changed
+
+- Plugin.php updated with frontend component initialization
+- Frontend assets now include localized script data with AJAX URL, nonce, and i18n strings
+- Widget registration added to init_frontend() method
+- Search, Shortcodes, and BlockRegistrar initialized when license is valid
+
+### Security
+
+- AJAX nonce verification on all frontend requests
+- Input sanitization on all search parameters
+- Output escaping in shortcode and widget templates
+- XSS prevention in JavaScript (textContent instead of innerHTML)
+
 ## [0.5.0] - 2026-01-31
 
 ### Added
@@ -290,6 +358,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Input sanitization and output escaping
 - Server secret masking in license settings
 
+[0.6.0]: https://src.bundespruefstelle.ch/magdev/wp-bnb/releases/tag/v0.6.0
 [0.5.0]: https://src.bundespruefstelle.ch/magdev/wp-bnb/releases/tag/v0.5.0
 [0.4.0]: https://src.bundespruefstelle.ch/magdev/wp-bnb/releases/tag/v0.4.0
 [0.3.0]: https://src.bundespruefstelle.ch/magdev/wp-bnb/releases/tag/v0.3.0