refactor(deployment): Remove WireGuard VPN dependency and restore public service access

Remove WireGuard integration from production deployment to simplify infrastructure:
- Remove docker-compose-direct-access.yml (VPN-bound services)
- Remove VPN-only middlewares from Grafana, Prometheus, Portainer
- Remove WireGuard middleware definitions from Traefik
- Remove WireGuard IPs (10.8.0.0/24) from Traefik forwarded headers

All monitoring services now publicly accessible via subdomains:
- grafana.michaelschiemer.de (with Grafana native auth)
- prometheus.michaelschiemer.de (with Basic Auth)
- portainer.michaelschiemer.de (with Portainer native auth)

All services use Let's Encrypt SSL certificates via Traefik.

tests/debug/generate-png-qrcodes.php

@@ -0,0 +1,92 @@
+<?php
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+use App\Framework\QrCode\QrCodeGenerator;
+use App\Framework\QrCode\ValueObjects\ErrorCorrectionLevel;
+use App\Framework\QrCode\ValueObjects\QrCodeConfig;
+use App\Framework\QrCode\ValueObjects\QrCodeVersion;
+use App\Framework\QrCode\ValueObjects\EncodingMode;
+
+echo "=== Generating PNG QR Codes ===\n\n";
+
+// Create output directory
+$outputDir = __DIR__ . '/test-qrcodes';
+if (!is_dir($outputDir)) {
+    mkdir($outputDir, 0755, true);
+}
+
+// Test data
+$testCases = [
+    ['data' => 'HELLO WORLD', 'filename' => 'hello-world.png'],
+    ['data' => 'A', 'filename' => 'single-char.png'],
+    ['data' => 'HELLO', 'filename' => 'hello.png'],
+    ['data' => 'https://example.com', 'filename' => 'url.png'],
+    ['data' => 'Test QR Code', 'filename' => 'test-text.png'],
+];
+
+$config = new QrCodeConfig(
+    version: QrCodeVersion::fromNumber(1),
+    errorCorrectionLevel: ErrorCorrectionLevel::M,
+    encodingMode: EncodingMode::BYTE
+);
+
+foreach ($testCases as $testCase) {
+    echo "Generating: '{$testCase['data']}'\n";
+    
+    $matrix = QrCodeGenerator::generate($testCase['data'], $config);
+    $size = $matrix->getSize();
+    
+    // Generate PNG with good quality
+    $moduleSize = 20; // 20px per module
+    $quietZone = 4;   // 4 modules quiet zone
+    $canvasSize = ($size + 2 * $quietZone) * $moduleSize;
+    
+    // Create image
+    $image = imagecreatetruecolor($canvasSize, $canvasSize);
+    $white = imagecolorallocate($image, 255, 255, 255);
+    $black = imagecolorallocate($image, 0, 0, 0);
+    
+    // Fill with white (background)
+    imagefill($image, 0, 0, $white);
+    
+    // Draw quiet zone (already white)
+    // Draw modules
+    $offset = $quietZone * $moduleSize;
+    
+    for ($row = 0; $row < $size; $row++) {
+        for ($col = 0; $col < $size; $col++) {
+            $isDark = $matrix->getModuleAt($row, $col)->isDark();
+            
+            if ($isDark) {
+                $x = $offset + ($col * $moduleSize);
+                $y = $offset + ($row * $moduleSize);
+                
+                imagefilledrectangle(
+                    $image,
+                    $x,
+                    $y,
+                    $x + $moduleSize - 1,
+                    $y + $moduleSize - 1,
+                    $black
+                );
+            }
+        }
+    }
+    
+    // Save PNG
+    $filepath = $outputDir . '/' . $testCase['filename'];
+    imagepng($image, $filepath, 0); // 0 = no compression for best quality
+    imagedestroy($image);
+    
+    $fileSize = filesize($filepath);
+    echo "  ✅ Saved: {$testCase['filename']} ({$fileSize} bytes, {$canvasSize}x{$canvasSize}px)\n\n";
+}
+
+echo "=== Summary ===\n";
+echo "PNG QR codes generated successfully!\n";
+echo "PNG format is more reliable for QR code scanners than SVG.\n";
+echo "Output directory: {$outputDir}\n";
+