refactor: Umstellung auf Mini-MVC-Architektur (Issue #46)

- Front Controller Pattern mit public/index.php als Einstiegspunkt
- Eigenes Routing (App\Core\Router) ohne externes Framework
- Controller: HomeController, ImpressumController, DatenschutzController
- Views mit gemeinsamem Layout (app/views/layouts/main.php)
- PSR-4 Autoloading
- Statische Assets nach public/ verschoben
- Alte Dateien (index.php, impressum.html, datenschutz.html) geloescht
- 301-Redirects fuer alte URLs
- PHP 8.5 kompatibel
- Apache DocumentRoot auf public/ gesetzt

app/core/View.php

@@ -0,0 +1,46 @@
+<?php
+
+declare(strict_types=1);
+
+namespace App\Core;
+
+class View
+{
+    private string $viewsPath;
+    private array $data = [];
+
+    public function __construct(?string $viewsPath = null)
+    {
+        $this->viewsPath = $viewsPath ?? dirname(__DIR__) . '/views';
+    }
+
+    public function assign(string $key, mixed $value): void
+    {
+        $this->data[$key] = $value;
+    }
+
+    public function render(string $view, string $layout = 'main'): void
+    {
+        $viewFile = $this->viewsPath . '/' . $view . '.php';
+        $layoutFile = $this->viewsPath . '/layouts/' . $layout . '.php';
+
+        if (!file_exists($viewFile)) {
+            throw new \RuntimeException("View {$view} nicht gefunden: {$viewFile}");
+        }
+
+        if (!file_exists($layoutFile)) {
+            throw new \RuntimeException("Layout {$layout} nicht gefunden: {$layoutFile}");
+        }
+
+        // Extract data to variables for the view
+        extract($this->data, EXTR_SKIP);
+
+        // Capture view content
+        ob_start();
+        require $viewFile;
+        $content = ob_get_clean();
+
+        // Render layout with $content
+        require $layoutFile;
+    }
+}