Implement dynamic language system with automatic detection

- Add getAvailableLanguages() method to scan lang directory automatically
- Add getNativeLanguageName() method for proper language display names
- Enhance SimpleTemplate engine to support array iteration with {{#array}} syntax
- Update header template to use dynamic language dropdown with native names
- Add German (de.php) and French (fr.php) language files as examples
- Fix search input text color to use black text for better visibility
- Languages now appear automatically when added to engine/lang/ without code changes

engine/lang/fr.php

@@ -0,0 +1,26 @@
+<?php
+return [
+    'site_title' => 'CodePress',
+    'home' => 'Home',
+    'search' => 'Search',
+    'search_placeholder' => 'Search...',
+    'search_button' => 'Search',
+    'welcome' => 'Welcome',
+    'created' => 'Created',
+    'modified' => 'Modified',
+    'author' => 'Author',
+    'manual' => 'Manual',
+    'no_content' => 'No content found',
+    'no_results' => 'No results found',
+    'results_found' => 'results found',
+    'breadcrumb_home' => 'Home',
+    'file_details' => 'File details',
+    'guide' => 'Guide',
+    'powered_by' => 'Powered by',
+    't_powered_by' => 'Powered by',
+    'directory_empty' => 'This directory is empty',
+    'page_not_found' => 'Page Not Found',
+    'page_not_found_text' => 'The page you are looking for does not exist.',
+    'mappen' => 'Folders',
+    'paginas' => 'Pages'
+];