v0.16.4 — root-turn watchdog

• Root-turn watchdog: an orchestrator that stays "active" while its timeline stops growing for 10 minutes is wedged in a provider turn, with queued steers piling up unprocessed behind it. Workers already had the three-strike retire; the root now gets stopped and auto-continued, which also flushes its message queue. (Field case: a root sat "Working…" for 20 minutes with zero output and a growing steer backlog while its goal showed no open work.)