test: set RUNNING_KUI_TEST=true for npm test target

this tells kui core not to use the second window instance magic from electron; this is because we want tests always to have their own fresh process

Author: starpit

package.json

@@ -34,7 +34,7 @@
     "start": "WATCH_ARGS='-open' npm run watch",
     "mirror": "T=$(mktemp -d); (cd $T && git clone --depth=1 git@github.com:guidebooks/store.git) && echo \"mirror stage in $T/store\" && ./bin/madwizard.js mirror $T/store/guidebooks ./store",
     "mirror-if-needed": "if [ ! -d ./store ]; then npm run mirror; fi",
-    "test": "playwright test --workers 1"
+    "test": "RUNNING_KUI_TEST=true playwright test --workers 1"
   },
   "keywords": [],
   "author": "@starpit",