fix(aorta): bound setup and run by timeout_seconds on daemon threads

[speriaswamy-amd]

Stack 5/6 — splits #171. Base: #390.

Why

Neither setup() nor run() put a deadline on their parallel per-node work, so a single stalled node hung the entire CVS invocation with no result. Hit live: an NCCL collective stalled on one node of a 2-node run and the process sat there indefinitely instead of reporting TIMEOUT.

ThreadPoolExecutor cannot fix this on its own — its workers are non-daemon, and CPython's atexit hook joins every one of them at interpreter shutdown regardless of shutdown(wait=False). A node stuck in a blocking Docker or SSH call would still wedge the process on the way out.

What changed

• _run_bounded_parallel() — runs each task on a daemon thread against a shared deadline, returning per-key results / errors / timeouts. Abandoned threads cannot block exit. Replaces ThreadPoolExecutor in both setup() and run().
• _setup_single_node() takes a cancel Event: if it finishes launching its container after setup() has given up, it tears that container down itself. Otherwise it would register into self._containers after teardown()'s one-time snapshot had already run, orphaning the container on the node. (Builds on fix(runner): tear down resources after a partially-successful setup #326.)

Test

ruff clean. Unit tests 623 → 631 (8 new, including a case asserting the worker thread is actually a daemon, and end-to-end setup()/run() timeout cases that assert the call returns promptly).

[amd-droy]

looks good. thanks.