Agent view exposes why a session is blocked and fan-out progress for scripted supervision

What this changes for operators

• claude agents --json now includes a waitingFor field naming what a blocked session is waiting on (e.g. a permission prompt), and claude agents rows now show done/total progress before detail when work is fanned out.
• Operators scripting or monitoring agent fleets can now programmatically distinguish 'stuck on a permission prompt' from other waits and read parallel-task completion, which is the difference between a watchdog that can unblock a session and one that can only detect silence.
• The operator action is to wire waitingFor and the progress counter into supervision tooling so stuck-agent triage stops requiring a human to open each session.