Add admin console with login, dashboard, content/config/plugin/user management

File-based admin panel accessible at /admin.php with:
- Session-based auth with bcrypt hashing and brute-force protection
- Dashboard with site statistics and quick actions
- Content manager: browse, create, edit, delete files
- Config editor with JSON validation
- Plugin overview with status indicators
- User management: add, remove, change passwords
- CSRF protection on all forms, path traversal prevention
- Updated README (NL/EN) and guides with admin documentation

guide/en.codepress.md

@@ -50,6 +50,17 @@ CodePress is a lightweight, file-based Content Management System built with PHP
 - **Dynamic layouts** with YAML frontmatter
 - **Sidebar support** with plugin integration and toggle function via breadcrumb
 
+### 🛡️ Admin Console
+- Built-in admin panel at `/admin.php`
+- **Dashboard** with statistics and quick actions
+- **Content management** - Browse, create, edit and delete files
+- **Configuration editor** - Edit `config.json` with JSON validation
+- **Plugin overview** - Status of all installed plugins
+- **User management** - Add, remove users and change passwords
+- Session-based authentication with bcrypt hashing
+- CSRF protection, brute-force lockout (5 attempts, 15 min)
+- Default login: `admin` / `admin` (change immediately after installation)
+
 ## Installation
 
 1. Clone or download CodePress files

guide/nl.codepress.md

@@ -50,6 +50,17 @@ CodePress CMS is een lichtgewicht, file-based content management systeem gebouwd
 - **Dynamic layouts** met YAML frontmatter
 - **Sidebar support** met plugin integratie en toggle functie via breadcrumb
 
+### 🛡️ Admin Console
+- Ingebouwd admin paneel op `/admin.php`
+- **Dashboard** met statistieken en snelle acties
+- **Content beheer** - Bestanden browsen, aanmaken, bewerken en verwijderen
+- **Configuratie editor** - `config.json` bewerken met JSON-validatie
+- **Plugin overzicht** - Status van alle geinstalleerde plugins
+- **Gebruikersbeheer** - Gebruikers toevoegen, verwijderen, wachtwoorden wijzigen
+- Session-based authenticatie met bcrypt hashing
+- CSRF-bescherming, brute-force lockout (5 pogingen, 15 min)
+- Standaard login: `admin` / `admin` (wijzig direct na installatie)
+
 ## Installatie
 
 1. Upload bestanden naar webserver