Copy the build worker's env when you rebuild its SHA by hand

If a background build worker compiles fine but a manual run of the same build script at the same SHA fails, diff the worker's exported environment before debugging the code. In one fork, the bundling step needs a published client artifact keyed by commit. Fork branches have none, so the worker pins a manifest URL through an env var, and a hand-run reload without it fails with 'no published client for this checkout'. Fix: export the same variables, or source the worker's env block, before the manual run.