Split list titlebar contracts

tests/Architecture/ListTitlebarMarkupContractTest.php

@@ -0,0 +1,18 @@
+<?php
+
+namespace MintyPHP\Tests\Architecture;
+
+use PHPUnit\Framework\TestCase;
+
+final class ListTitlebarMarkupContractTest extends TestCase
+{
+    use ProjectFileAssertionSupport;
+
+    public function testTemplatesDoNotInlineLegacyListTitlebarMarkup(): void
+    {
+        foreach (ListTitlebarContractFiles::titlebarTemplateFiles() as $file) {
+            $content = $this->readProjectFile($file);
+            $this->assertSame(0, preg_match('/<div\s+class=\"app-list-titlebar\"/', $content), $file);
+        }
+    }
+}