A build-only compile queue leaves no app for the user to test

If a shared local build queue compiles with a build-only flag (for example a reload script's --build-only), a PASS only proves the code compiles. The script deletes the staged app bundle afterwards, so nothing launchable remains, and only the warm DerivedData cache survives. To hand a user a test build, pause the queue worker so nothing moves the checkout, then run the full reload at the passing SHA in a checkout that has its submodules. It's mostly incremental thanks to the warm cache. Don't launch it for the user. Plan for this step up front, or the 'ready to try' moment slips.