Put PTT behind 'feature flag'

AKA does the URL hash start with '#ptt'

This will let us merge PTT back to the main branch

.vscode/settings.json

@@ -1,5 +1,5 @@
 {
-  "editor.formatOnSave": true,
+  "editor.formatOnSave": false,
   "editor.insertSpaces": true,
   "editor.tabSize": 2
-}
+}