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.php

@@ -0,0 +1,99 @@
+<?php
+
+declare(strict_types=1);
+
+require_once __DIR__ . '/../../vendor/autoload.php';
+
+use App\Framework\QrCode\ErrorCorrection\ReedSolomonEncoder;
+
+echo "=== Polynomial Division Step-by-Step ===\n\n";
+
+// Test with simple data to trace the algorithm
+$data = [1, 2, 3];
+$ecCodewords = 3;
+
+$rs = new ReedSolomonEncoder();
+$reflection = new ReflectionClass($rs);
+
+// Get generator polynomial
+$getGeneratorMethod = $reflection->getMethod('getGeneratorPolynomial');
+$getGeneratorMethod->setAccessible(true);
+$generator = $getGeneratorMethod->invoke($rs, $ecCodewords);
+
+echo "Data: " . implode(', ', $data) . "\n";
+echo "EC codewords needed: {$ecCodewords}\n";
+echo "Generator polynomial (degree {$ecCodewords}): " . implode(', ', $generator) . "\n\n";
+
+// Manually trace the algorithm
+echo "=== Algorithm Trace ===\n";
+
+// Step 1: Create message polynomial
+$messagePoly = array_merge($data, array_fill(0, $ecCodewords, 0));
+echo "Step 1 - Message polynomial (data + zeros):\n";
+echo "  [" . implode(', ', $messagePoly) . "]\n\n";
+
+// Step 2: Polynomial division
+echo "Step 2 - Polynomial division:\n";
+
+$gfMultiplyMethod = $reflection->getMethod('gfMultiply');
+$gfMultiplyMethod->setAccessible(true);
+
+$traceMessagePoly = $messagePoly;
+
+for ($i = 0; $i < count($data); $i++) {
+    $coefficient = $traceMessagePoly[$i];
+    
+    if ($coefficient !== 0) {
+        echo "  Iteration {$i}: coefficient = {$coefficient}\n";
+        echo "    Before: [" . implode(', ', $traceMessagePoly) . "]\n";
+        
+        for ($j = 0; $j < count($generator); $j++) {
+            $multiplied = $gfMultiplyMethod->invoke($rs, $generator[$j], $coefficient);
+            $oldValue = $traceMessagePoly[$i + $j];
+            $traceMessagePoly[$i + $j] ^= $multiplied;
+            $newValue = $traceMessagePoly[$i + $j];
+            
+            if ($oldValue !== $newValue) {
+                echo "      [{$i}+{$j}] = {$oldValue} XOR {$multiplied} = {$newValue}\n";
+            }
+        }
+        
+        echo "    After:  [" . implode(', ', $traceMessagePoly) . "]\n\n";
+    } else {
+        echo "  Iteration {$i}: coefficient = 0 (skip)\n\n";
+    }
+}
+
+// Step 3: Extract EC codewords
+$ec = array_slice($traceMessagePoly, count($data));
+echo "Step 3 - EC codewords (last {$ecCodewords} coefficients):\n";
+echo "  [" . implode(', ', $ec) . "]\n\n";
+
+// Verify with actual implementation
+$actualEC = $rs->encode($data, $ecCodewords);
+echo "Actual EC codewords from implementation:\n";
+echo "  [" . implode(', ', $actualEC) . "]\n\n";
+
+if ($ec === $actualEC) {
+    echo "✅ Traced algorithm matches implementation!\n";
+} else {
+    echo "❌ Traced algorithm doesn't match implementation!\n";
+    echo "Differences:\n";
+    for ($i = 0; $i < min(count($ec), count($actualEC)); $i++) {
+        if ($ec[$i] !== $actualEC[$i]) {
+            echo "  Position {$i}: traced={$ec[$i]}, actual={$actualEC[$i]}\n";
+        }
+    }
+}
+
+// Test with our actual QR code data
+echo "\n=== Test with QR Code Data ===\n";
+$qrData = [64, 180, 132, 84, 196, 196, 242, 5, 116, 245, 36, 196, 64, 236, 17, 236];
+$qrEC = $rs->encode($qrData, 10);
+
+echo "QR data codewords (16):\n";
+echo "  " . implode(', ', $qrData) . "\n\n";
+echo "QR EC codewords (10):\n";
+echo "  " . implode(', ', $qrEC) . "\n\n";
+
+