`script-test-agent-bao-fetch` executes the rendered `ExecStart` of
`hive-agent-forge-token` and `hive-agent-queue-credential` under
`umask 0377`, with a stub `bao` first on the unit's own PATH. It covers
every error branch, the happy path, forge rotation/unchanged, and 0400
files already in place: the redirect failure #4736 fixed, whose live
symptom was `bao.err: Permission denied` reported as a refused
certificate. The TLS-alert fixture is the `unknown certificate
authority` error h-atlas's identity check got from the store.
#4736 claimed this test but never committed it; the two module-eval
suites for these units only evaluate the config.
Closes#4748
202f7f7c83