feat(wpmc S4): TermMeta registers ACF main_page_alt on taxonomy town

Add acf-stubs.php + TestCase::setUp() require-after-Patchwork pattern so
acf_add_local_field_group is Patchwork-instrumented and re-interceptable
across FieldGroupTest and TermMetaTest in the same PHP process.

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

tests/acf-stubs.php

@@ -0,0 +1,18 @@
+<?php
+declare(strict_types=1);
+
+/**
+ * Minimal ACF function stubs for the test suite.
+ *
+ * This file is required from TestCase::setUp() AFTER Brain\Monkey\setUp() so
+ * that Patchwork's stream wrapper instruments these functions and can redefine
+ * them across successive test classes in the same PHP process.
+ *
+ * Functions declared via eval() cannot be re-intercepted by Patchwork after
+ * restoreAll(); functions from a real file loaded through Patchwork's stream
+ * wrapper can.
+ */
+
+if (!function_exists('acf_add_local_field_group')) {
+    function acf_add_local_field_group(array $args = []): void {}
+}