Only pass the process_started hook when live run state tracking is active,
so existing rsync call sites and tests without that hook remain compatible.
Refs #54
Record rsync process pid and execution phase while normal backup runs are
active so the worker can reconcile stale running rows when rsync has
already disappeared.
Keep finalizing runs out of the missing-process path to avoid marking
slow post-rsync stats collection as a failed transfer.
Closes#54
Record live rsync log paths for normal backup runs so the worker can
recover stale running state after terminal rsync errors.
Treat rsync vanished-file exit code 24 as a warning and keep the
completed snapshot instead of failing the run into incomplete state.
Closes#54
