feat: implement 5 new advanced WCAG rules (ColorContrast, DuplicateId, TabindexOrder, AriaRole, IframeTitle)

src/Rules/TabindexOrder.php

@@ -0,0 +1,34 @@
+<?php
+
+namespace YakNet\AccessibilityConsole\Rules;
+
+use DOMElement;
+use YakNet\AccessibilityConsole\Core\Severity;
+use YakNet\AccessibilityConsole\Core\Violation;
+use YakNet\AccessibilityConsole\Core\WCAGStandard;
+
+class TabindexOrder extends AbstractRule
+{
+    public function getId(): string { return 'WCAG_2_4_3_TABINDEX'; }
+    public function getDescription(): string { return 'Avoid positive tabindex values to maintain natural keyboard focus order.'; }
+    public function getStandard(): WCAGStandard { return WCAGStandard::A; }
+    public function getSeverity(): Severity { return Severity::WARNING; }
+
+    public function check(DOMElement $element): ?Violation
+    {
+        if ($element->hasAttribute('tabindex')) {
+            $tabindex = $element->getAttribute('tabindex');
+            if (is_numeric($tabindex)) {
+                $val = (int)$tabindex;
+                if ($val > 0) {
+                    return $this->createViolation(
+                        $element,
+                        "Avoid positive tabindex values (tabindex=\"{$val}\") to preserve the natural tab order.",
+                        "Remove the positive tabindex or change it to \"0\" or \"-1\"."
+                    );
+                }
+            }
+        }
+        return null;
+    }
+}