fix(cli): reject exiting dispatch leaders on macOS

[wgqqqqq]

Summary

Backport only the macOS dispatch fix from #2497 to 1.0.0-explore:

• reject ps states carrying the exiting E modifier before SIGKILL escalation
• accept only known live primary states (I, R, S, T, U)
• fail closed for empty, zombie, exiting, and unknown states
• add focused state-parser coverage

No telemetry/configuration changes from #2497 are included.

Root cause

The intermittent failure exposed a real exit-window race. kill(pid, 0) can still observe a leader that is already trying to exit, while macOS ps marks that state with the E modifier. The previous zombie-only check accepted values such as SE and UEs, re-authenticated the leader, and allowed SIGKILL escalation after SIGTERM had already initiated exit.

Signal ordering and timeout behavior remain unchanged.

Verification

• source file is byte-identical to the merged main fix at eadedaded
• fix: preserve models and reject exiting dispatch leaders #2497 passed macOS CLI and Rust build checks on main
• focused parser tests cover live, zombie, exiting, empty, and unknown states
• this PR runs the current impact-selected CI without desktop package producers