Fix security vulnerabilities, remove dead code, and improve code quality

- Fix path traversal with realpath() validation in getPage() and executePhpFile()
- Remove insecure JWT secret fallback, require JWT_SECRET env var
- Fix IP spoofing by only trusting proxy headers from configured proxies
- Add Secure/HttpOnly/SameSite flags to all cookies
- Use env var for debug mode instead of hardcoded true
- Fix operator precedence bug in MQTTTracker track_user_flows check
- Remove dead code: duplicate is_dir() block, unused scanForPageNames()
- Remove htmlspecialchars() from filesystem path operations
- Remove duplicate require_once calls and redundant autoloader includes
- Fix unclosed </div> in getDirectoryListing()
- Escape breadcrumb titles and add lang param to search result URLs
- Make language prefixes dynamic from config instead of hardcoded nl|en
- Make HTML lang attribute dynamic, add go_to translation key
- Add aria-label/aria-expanded to sidebar toggle for accessibility
- Fix event listener leak in app.js using event delegation
- Remove console.log from production code
- Update guides (NL/EN) with sidebar toggle documentation
- Add TODO.md documenting all identified improvements

guide/en.codepress.md

@@ -12,8 +12,9 @@ CodePress is a lightweight, file-based Content Management System built with PHP
 - Home button with icon
 - Automatic menu generation
 - Responsive design
-- Breadcrumb navigation
+- Breadcrumb navigation with sidebar toggle
 - Active state marking
+- **Sidebar toggle** - Button placed left of HOME in the breadcrumb to open/close the sidebar. The icon changes between open and closed state. The choice is preserved during the session
 
 ### 📄 Content Types
 - **Markdown (.md)** - CommonMark support
@@ -47,7 +48,7 @@ CodePress is a lightweight, file-based Content Management System built with PHP
 - Mustache templates
 - Semantic HTML5 structure
 - **Dynamic layouts** with YAML frontmatter
-- **Sidebar support** with plugin integration
+- **Sidebar support** with plugin integration and toggle function via breadcrumb
 
 ## Installation
 

guide/nl.codepress.md

@@ -12,8 +12,9 @@ CodePress CMS is een lichtgewicht, file-based content management systeem gebouwd
 - Home knop met icoon
 - Automatische menu generatie
 - Responsive design
-- Breadcrumb navigatie
+- Breadcrumb navigatie met sidebar toggle
 - Active state marking
+- **Sidebar toggle** - Knop links van HOME in de breadcrumb om de sidebar te openen/sluiten. Het icoon wisselt tussen open en gesloten status. De keuze blijft behouden tijdens de sessie
 
 ### 📄 Content Types
 - **Markdown (.md)** - CommonMark ondersteuning
@@ -47,7 +48,7 @@ CodePress CMS is een lichtgewicht, file-based content management systeem gebouwd
 - Mustache templates
 - Semantic HTML5 structuur
 - **Dynamic layouts** met YAML frontmatter
-- **Sidebar support** met plugin integratie
+- **Sidebar support** met plugin integratie en toggle functie via breadcrumb
 
 ## Installatie