Command tests did not assert behavior when exec fails in child processes.
I added deterministic regression coverage that forces execl/execlp failure and
verifies non-zero exit status propagation for both open() and forkExec paths.
Signed-off-by: Austin Horstman <khaneliman12@gmail.com>
We needed a regression test for reassignment safety after lifecycle fixes.
I added a subprocess test that reassigns SleeperThread workers and verifies the
process exits normally instead of terminating.
Signed-off-by: Austin Horstman <khaneliman12@gmail.com>