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/TermMetaTest.php

@@ -0,0 +1,62 @@
+<?php
+declare(strict_types=1);
+
+namespace WPMultiCity\Tests;
+
+use WPMultiCity\TermMeta;
+
+final class TermMetaTest extends TestCase
+{
+    public function test_register_attaches_acf_init_action(): void
+    {
+        TermMeta::register();
+
+        self::assertNotFalse(
+            has_action('acf/init', [TermMeta::class, 'do_register']),
+            'TermMeta::register() must hook acf/init'
+        );
+    }
+
+    public function test_do_register_is_noop_when_acf_missing(): void
+    {
+        \Brain\Monkey\Functions\when('function_exists')->alias(function ($name) {
+            return $name !== 'acf_add_local_field_group';
+        });
+
+        // acf_add_local_field_group is NOT stubbed here: if do_register() called it,
+        // the Brain\Monkey eval-stub would throw MissingFunctionExpectations.
+        // We just verify the method returns without error.
+        TermMeta::do_register();
+
+        self::assertTrue(true);
+    }
+
+    public function test_do_register_registers_main_page_alt_field_group(): void
+    {
+        \Brain\Monkey\Functions\when('function_exists')->alias(function ($name) {
+            return $name === 'acf_add_local_field_group';
+        });
+
+        $captured = null;
+        \Brain\Monkey\Functions\expect('acf_add_local_field_group')
+            ->once()
+            ->with(\Mockery::on(function ($group) use (&$captured) {
+                $captured = $group;
+                return true;
+            }));
+
+        TermMeta::do_register();
+
+        self::assertSame('group_wpmc_town_main_page', $captured['key']);
+        self::assertSame(
+            [[['param' => 'taxonomy', 'operator' => '==', 'value' => 'town']]],
+            $captured['location']
+        );
+        self::assertCount(1, $captured['fields']);
+        self::assertSame('field_wpmc_main_page_alt', $captured['fields'][0]['key']);
+        self::assertSame('main_page_alt', $captured['fields'][0]['name']);
+        self::assertSame('post_object', $captured['fields'][0]['type']);
+        self::assertSame('id', $captured['fields'][0]['return_format']);
+        self::assertSame(['page'], $captured['fields'][0]['post_type']);
+    }
+}