Scope hey-woo-tests mapping to the tests environment only

Moves the `wp-content/plugins/hey-woo-tests` directory mapping from the
top-level into `env.tests.mappings` so it is only present in the wp-env
tests environment. Since wp-env merges mappings across environments, the
tests-cli container still gets both paths, while the development
environment now only mounts the plugin once — fixing the duplicate entry
in the WP admin plugins list.

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

Author: louwie17

.wp-env.json

@@ -2,7 +2,6 @@
   "core": "WordPress/WordPress#6.9",
   "plugins": ["https://downloads.wordpress.org/plugin/woocommerce.zip"],
   "mappings": {
-    "wp-content/plugins/hey-woo-tests": ".",
     "wp-content/plugins/hey-woo": ".",
     "wp-content/mu-plugins": "./tools/mu-plugins"
   },
@@ -13,5 +12,12 @@
   },
   "lifecycleScripts": {
     "afterStart": "wp-env run cli -- wp option update woocommerce_feature_mcp_integration_enabled yes && wp-env run cli -- wp plugin activate woocommerce hey-woo && wp-env run cli -- wp wc tool run install_pages --user=admin && wp-env run cli -- wp option update woocommerce_store_address '123 Main Street' && wp-env run cli -- wp option update woocommerce_store_city 'London' && wp-env run cli -- wp option update woocommerce_store_postcode 'EC1A 1BB' && wp-env run cli -- wp option update woocommerce_default_country 'GB' && wp-env run cli -- wp option update woocommerce_currency 'GBP'"
+  },
+  "env": {
+    "tests": {
+      "mappings": {
+        "wp-content/plugins/hey-woo-tests": "."
+      }
+    }
   }
 }