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/test-polynomial-division-detailed.php

@@ -0,0 +1,87 @@
+<?php
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;
+
+echo "=== Detailed Polynomial Division Test ===\n\n";
+
+// Test with simple known case
+$data = [1];
+$ecCodewords = 2;
+
+$rs = new ReedSolomonEncoder();
+$reflection = new ReflectionClass($rs);
+
+// Get generator
+$getGeneratorMethod = $reflection->getMethod('getGeneratorPolynomial');
+$getGeneratorMethod->setAccessible(true);
+$generator = $getGeneratorMethod->invoke($rs, $ecCodewords);
+
+echo "Data: " . implode(', ', $data) . "\n";
+echo "EC codewords: {$ecCodewords}\n";
+echo "Generator: " . implode(', ', $generator) . "\n\n";
+
+// Manual trace
+$msg = array_merge($data, array_fill(0, $ecCodewords, 0));
+echo "Initial message: " . implode(', ', $msg) . "\n\n";
+
+$gfMultiplyMethod = $reflection->getMethod('gfMultiply');
+$gfMultiplyMethod->setAccessible(true);
+
+echo "Step-by-step division:\n";
+for ($i = 0; $i < count($data); $i++) {
+    $coeff = $msg[$i];
+    echo "Iteration {$i}: coefficient = {$coeff}\n";
+    
+    if ($coeff !== 0) {
+        echo "  Before: " . implode(', ', $msg) . "\n";
+        
+        // Current implementation
+        $msg[$i] = 0;
+        for ($j = 1; $j < count($generator); $j++) {
+            $index = $i + $j;
+            if ($index < count($msg)) {
+                $multiplied = $gfMultiplyMethod->invoke($rs, $generator[$j], $coeff);
+                $old = $msg[$index];
+                $msg[$index] ^= $multiplied;
+                echo "    [{$index}]: {$old} XOR {$multiplied} = {$msg[$index]}\n";
+            }
+        }
+        
+        echo "  After:  " . implode(', ', $msg) . "\n\n";
+    }
+}
+
+$ec = array_slice($msg, count($data));
+echo "EC codewords: " . implode(', ', $ec) . "\n\n";
+
+// Compare with actual
+$actualEC = $rs->encode($data, $ecCodewords);
+echo "Actual EC: " . implode(', ', $actualEC) . "\n\n";
+
+if ($ec === $actualEC) {
+    echo "✅ Manual trace matches implementation\n";
+} else {
+    echo "❌ Manual trace doesn't match\n";
+}
+
+// Now test what the correct algorithm should be
+echo "\n=== Correct Algorithm (from qrcode.js) ===\n";
+// The algorithm from qrcode.js:
+// for (var i = 0; i < data.length; i++) {
+//   var lead = msg[i];
+//   if (lead !== 0) {
+//     msg[i] = 0;
+//     for (var j = 1; j < gen.length; j++) {
+//       msg[i + j] ^= gfMult(gen[j], lead);
+//     }
+//   }
+// }
+
+// This is exactly what we're doing! So the algorithm should be correct.
+// The problem must be with the generator polynomial format or the GF multiplication.
+
+