chore: init wp-multi-city v0.1.0 with S1 skeleton + S2 design spec

S1 skeleton (cp-8ci, already done):
- wp-multi-city.php with header, constants, hooks bootstrap
- includes/class-plugin.php with PSR-4-ish autoloader, ACF dependency guard
- includes/class-activator.php placeholder
- composer.json (PHP 8.0, phpunit dev)
- README.md with roadmap
- uninstall.php placeholder

S2 design (cp-q7g):
- docs/superpowers/specs/2026-05-12-s2-taxonomy-cpt-acf-design.md

wp-multi-city.php

@@ -0,0 +1,30 @@
+<?php
+/**
+ * Plugin Name: WP Multi City
+ * Description: Мультигородская подсистема: taxonomy town, шорткоды для подстановки по городу, роутер /{city}/{path}/, page-clones по городам.
+ * Version: 0.1.0
+ * Author: Vladimir Bryzgalov
+ * Requires PHP: 8.0
+ * Requires at least: 6.0
+ * License: GPLv2 or later
+ * Text Domain: wp-multi-city
+ */
+
+declare(strict_types=1);
+
+if (!defined('ABSPATH')) exit;
+
+define('WPMC_PLUGIN_FILE', __FILE__);
+define('WPMC_PLUGIN_DIR', plugin_dir_path(__FILE__));
+define('WPMC_PLUGIN_URL', plugin_dir_url(__FILE__));
+define('WPMC_VERSION', '0.1.0');
+
+require_once WPMC_PLUGIN_DIR . 'includes/class-plugin.php';
+\WPMultiCity\Plugin::register_autoloader();
+
+register_activation_hook(__FILE__, ['\\WPMultiCity\\Activator', 'activate']);
+register_deactivation_hook(__FILE__, ['\\WPMultiCity\\Activator', 'deactivate']);
+
+add_action('plugins_loaded', static function (): void {
+    \WPMultiCity\Plugin::instance()->boot();
+});