feat(wpmc S2): PostType::register() attaches init hook

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

includes/class-post-type.php

@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity;
+
+final class PostType
+{
+    public const SLUG = 'shortcode-town';
+
+    public static function register(): void
+    {
+        add_action('init', [self::class, 'do_register']);
+    }
+
+    public static function do_register(): void
+    {
+        // Implementation filled in Task 9.
+    }
+}

tests/PostTypeTest.php

@@ -0,0 +1,19 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity\Tests;
+
+use WPMultiCity\PostType;
+
+final class PostTypeTest extends TestCase
+{
+    public function test_register_attaches_init_action(): void
+    {
+        PostType::register();
+
+        self::assertNotFalse(
+            has_action('init', [PostType::class, 'do_register']),
+            'PostType::register() must attach init action with do_register handler'
+        );
+    }
+}