## Complete Multi-language System & Navigation Enhancement

### Features Added:
- **Multi-language Support**: Dutch/English with URL-based switching (?lang=nl|en)
- **Theme Customization**: Configurable header/navigation colors via config.json
- **Navigation Improvements**: Active states, dropdown chevron icons, visual distinction
- **Mobile Responsive**: Separate desktop/mobile search layouts
- **Template System**: Fixed rendering pipeline for all partials

### Technical Fixes:
- Fixed language file path (engine/lang/ vs engine/core/class/../lang/)
- Added template data rendering to layout template
- Implemented navigation active state for default/home page
- Added chevron icons to dropdown folders for visual distinction
- Removed hardcoded navigation opacity class for theme colors

### Files Modified:
- config.json: Added theme and language configuration
- engine/core/class/CodePressCMS.php: Multi-language and navigation logic
- engine/templates/: Enhanced header, footer, navigation, layout
- engine/lang/: Dutch and English translation files
- public/assets/css/mobile.css: Mobile responsive fixes

### Result:
Fully functional multi-language CMS with proper navigation states and theme customization.

engine/templates/assets/navigation.mustache

@@ -1,10 +1,10 @@
-<nav class="navigation-section border-bottom navigation-50-opacity">
+<nav class="navigation-section">
     <div class="container-fluid">
         <div class="row align-items-center">
             <div class="col">
                 <ul class="nav nav-tabs flex-wrap">
 <li class="nav-item">
-                    <a class="nav-link" href="?page={{homepage}}">
+                    <a class="nav-link {{home_active_class}}" href="?page={{homepage}}">
                         <i class="bi bi-house"></i> {{homepage_title}}
                     </a>
                 </li>