Implement comprehensive stock management integration (v1.1.0)

Added complete inventory tracking system for composable products:
- Stock validation during product selection and add-to-cart
- Automatic stock deduction on order completion/processing
- Automatic stock restoration on order cancellation/refund
- Stock status indicators with visual feedback (In stock, Low stock, Out of stock)
- Prevention of out-of-stock item selection
- Low stock warnings when 5 or fewer items remain
- Order notes documenting all stock changes

New files:
- includes/Stock_Manager.php: Core stock management logic

Modified files:
- includes/Cart_Handler.php: Integrated stock validation
- includes/Product_Selector.php: Added stock info to product data
- includes/Plugin.php: Added Stock_Manager to includes
- templates/product-selector.twig: Stock status display
- assets/css/frontend.css: Stock indicator styling
- languages/*.pot/*.po: 8 new translatable strings

Version bumped to 1.1.0 with updated CHANGELOG.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

CHANGELOG.md

@@ -5,6 +5,35 @@ 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).
 
+## [1.1.0] - 2024-12-31
+
+### Added
+
+- **Stock Management Integration**: Complete inventory tracking system for composable products
+  - Stock validation during product selection and add-to-cart
+  - Automatic stock deduction when orders are completed/processed
+  - Automatic stock restoration on order cancellation/refund
+  - Stock status indicators in product selector (In stock, Low stock, Out of stock)
+  - Visual feedback for out-of-stock items (disabled checkboxes, reduced opacity)
+  - Low stock warnings when 5 or fewer items remain
+  - Prevention of out-of-stock item selection
+  - Order notes documenting stock changes
+
+### Technical
+
+- New `Stock_Manager` class handling all stock operations
+- Integration with WooCommerce order status hooks
+- Stock information passed to frontend via Twig template
+- Enhanced CSS styling for stock status badges
+- Stock data stored in order item meta for accurate tracking
+- Backorder support detection and handling
+
+### Translation
+
+- Added 8 new translatable strings for stock messages
+- Updated Italian (Switzerland) translation with stock-related terms
+- Updated translation template (.pot file)
+
 ## [1.0.1] - 2024-12-31
 
 ### Fixed