- except clause in cancel_benchmark/cancel_finetune narrowed from Exception
to _subprocess.TimeoutExpired (C1)
- _cancelled_jobs.discard() called after registering new proc to prevent
a stale flag from a prior run masking errors (I2)
- local `import subprocess` removed from run_benchmark and
run_finetune_endpoint; all Popen calls updated to _subprocess.Popen (I1)
- test patch targets updated from subprocess.Popen to app.api._subprocess.Popen;
cancelled-event tests updated to set flag in proc.wait() side-effect so
the discard-on-new-run logic is exercised correctly
Adds POST /api/benchmark/cancel and POST /api/finetune/cancel endpoints
that terminate the running subprocess (kill on 3s timeout), and updates
the run generators to emit a cancelled SSE event instead of error when
the job was intentionally stopped.
