feat(auth): harden login flows and finalize quality-check coverage

tests/Architecture/AuthRegisterSecurityContractTest.php

@@ -0,0 +1,23 @@
+<?php
+
+namespace MintyPHP\Tests\Architecture;
+
+use PHPUnit\Framework\TestCase;
+
+class AuthRegisterSecurityContractTest extends TestCase
+{
+    use ProjectFileAssertionSupport;
+
+    public function testRegisterPageVerifiesCsrfBeforeHandlingPostPayload(): void
+    {
+        $content = $this->readProjectFile('pages/auth/register().php');
+
+        $this->assertStringContainsString("if (\$request->isMethod('POST')) {", $content);
+        $this->assertStringContainsString("if (!Session::checkCsrfToken()) {", $content);
+        $this->assertStringContainsString("t('Form expired, please try again')", $content);
+        $this->assertMatchesRegularExpression(
+            '/if \(\$request->isMethod\(\'POST\'\)\) \{\s*if \(!Session::checkCsrfToken\(\)\) \{/s',
+            $content
+        );
+    }
+}