Add complete translation files for all planned locales

Created translation (.po) files for all 6 planned locales:

German locales:
- de_DE: German (Germany, formal "Sie")
- de_DE_informal: German (Germany, informal "du")
- de_CH: German (Switzerland, formal "Sie")
- de_CH_informal: German (Switzerland, informal "du")

Swiss locales:
- fr_CH: French (Switzerland)
- it_CH: Italian (Switzerland)

All translations include:
- Complete translation of all 40+ user-facing strings
- Proper plural forms configuration
- Swiss locale examples using CHF currency formatting
- Formal/informal variants where appropriate
- Locale-specific terminology (e.g., "Artikelnummer" vs "référence")

Translation coverage:
✓ Plugin activation messages
✓ Admin settings interface
✓ Product data tab fields
✓ Frontend product selector
✓ Cart and checkout messages
✓ Error and validation messages

Ready for compilation to .mo files for production use.

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

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

CLAUDE.md

@@ -61,13 +61,12 @@ Note: Swiss locales should use CHF currency formatting in examples (e.g., "CHF 5
 
 ### Create releases
 
-**Important Notes**
-
 - The `vendor/` directory MUST be included in releases (Twig dependency required for runtime)
 - Running zip from wrong directory creates empty or malformed archives
 - Exclusion patterns must match the relative path structure used in zip command
 - Always verify the package with `unzip -l` and test extraction before committing
-- The `wp-core/` and `wp-plugins/` directories MUST NOT be included in releases!
+- The `wp-core/` and `wp-plugins/` directories MUST NOT be included in releases
+- Releases are stored in `releases/` including checksums
 
 **Important Git Notes:**
 
@@ -95,7 +94,7 @@ Note: Swiss locales should use CHF currency formatting in examples (e.g., "CHF 5
 
 ## Project Structure
 
-```
+```txt
 wc-composable-product/
 ├── assets/
 │   ├── css/
@@ -162,17 +161,20 @@ wc-composable-product/
 ### Data Flow
 
 **Product Creation:**
+
 1. Admin selects "Composable product" type
 2. Configures criteria, limits, pricing in product data tab
 3. Metadata saved: `_composable_*` fields
 
 **Frontend Display:**
+
 1. `Cart_Handler::render_product_selector()` called on product page
 2. `Product_Type::get_available_products()` queries matching products
 3. `Product_Selector::render()` passes data to Twig template
 4. JavaScript handles selection UI and AJAX
 
 **Add to Cart:**
+
 1. Customer selects products (JS validates limit)
 2. AJAX request with `composable_products[]` array
 3. `Cart_Handler::validate_add_to_cart()` server-side validation
@@ -182,6 +184,7 @@ wc-composable-product/
 ## Development Workflow
 
 ### Initial Setup
+
 ```bash
 composer install
 ```
@@ -226,6 +229,7 @@ unzip -l wc-composable-product-vX.X.X.zip
 ### v1.0.0 - Initial Implementation (2024-12-31)
 
 **What was built:**
+
 - Complete plugin implementation from scratch
 - All 6 core PHP classes with PSR-4 autoloading
 - Twig template system integration
@@ -235,6 +239,7 @@ unzip -l wc-composable-product-vX.X.X.zip
 - Comprehensive documentation (README, INSTALL, IMPLEMENTATION)
 
 **Key decisions made:**
+
 - Used Singleton pattern for main Plugin class
 - Twig for templating (per requirements)
 - Vanilla JS + jQuery for frontend (WooCommerce standard)
@@ -245,11 +250,13 @@ unzip -l wc-composable-product-vX.X.X.zip
 **Files created:** 21 files, 2,628 lines of code
 
 **Git workflow:**
+
 - Initial commit to `main` branch
 - Created `dev` branch from `main`
 - Both branches in sync at v1.0.0
 
 **What works:**
+
 - Product type registration ✓
 - Admin product data tab ✓
 - Category/tag/SKU selection ✓
@@ -259,12 +266,14 @@ unzip -l wc-composable-product-vX.X.X.zip
 - Pricing calculation (both modes) ✓
 
 **Known limitations:**
+
 - Currently only simple products in selection (not variable)
 - No grouped product support
 - No automatic stock deduction for selected items
 - Template cache requires manual clearing after updates
 
 **Future enhancements to consider:**
+
 - Variable product support
 - Quantity selection per item
 - Visual bundle preview
@@ -277,6 +286,7 @@ unzip -l wc-composable-product-vX.X.X.zip
 **For AI Assistants:**
 
 When starting a new session on this project:
+
 1. Read this CLAUDE.md file first
 2. Review IMPLEMENTATION.md for technical details
 3. Check git log for recent changes