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

composer.json

@@ -0,0 +1,23 @@
+{
+  "name": "bryzgalov/wp-multi-city",
+  "description": "Multi-city subsystem for WordPress: taxonomy town, per-city shortcodes, /{city}/{path}/ router, page clones.",
+  "type": "wordpress-plugin",
+  "license": "GPL-2.0-or-later",
+  "require": {
+    "php": ">=8.0"
+  },
+  "require-dev": {
+    "phpunit/phpunit": "^9.6"
+  },
+  "autoload-dev": {
+    "psr-4": {
+      "WPMultiCity\\Tests\\": "tests/"
+    }
+  },
+  "scripts": {
+    "test": "phpunit"
+  },
+  "config": {
+    "sort-packages": true
+  }
+}