Fix internal markdown links and auto-linking language persistence

- Add language parameter to autoLinkPageTitles() method
- Fix internal links to include current language (?page=x&lang=en)
- Remove broken header ID syntax from English guide
- Ensure all auto-generated internal links maintain language context
- Internal page links now work correctly across language switches

engine/core/class/CodePressCMS.php

@@ -434,7 +434,7 @@ class CodePressCMS {
                     return $text; // Don't link existing links, current page title, or H1 headings
                 }
                 
-                return '<a href="?page=' . $pagePath . '" class="auto-link" title="Ga naar ' . htmlspecialchars($pageTitle) . '">' . $text . '</a>';
+                return '<a href="?page=' . $pagePath . '&lang=' . $this->currentLanguage . '" class="auto-link" title="Ga naar ' . htmlspecialchars($pageTitle) . '">' . $text . '</a>';
             };
             
             $content = preg_replace_callback($pattern, $replacement, $content);