TDD expected-fail tests proving bug #822 exists:
CheckpointService.rollback_to_checkpoint() returns a successful
RollbackResult but does not execute git reset --hard. Files modified
after the checkpoint remain unchanged after rollback.
Also fixes Robot Framework timeout robustness across the entire test
suite: all Run Process calls now use on_timeout=kill (prevents
SIGTERM-induced -15 exit codes under CI load) and timeouts increased
to 120s (prevents premature kills during heavy parallel execution).
ISSUES CLOSED: #839
brent.edwards