fix: allow orchestrator to idle when sub-agents are active

[flobo3]

Title: fix: allow orchestrator to idle when sub-agents are active

Fixes #1721

When running in modes like ralplan or ralph, the orchestrator delegates work to sub-agents via the Agent tool. While the sub-agent is actively working, the orchestrator naturally has nothing to do and tries to stop/idle. However, the Stop hook (persistent-mode / skill-state) was blocking this, forcing the orchestrator into a meaningless polling loop.

This PR adds a check in checkPersistentModes to consult the subagent-tracker. If there are active sub-agents running (getActiveAgentCount > 0), the orchestrator is correctly waiting for them to finish, and the stop event is allowed to proceed (idle state).

[Yeachan-Heo]

Thanks for the contribution! Two things:

1. Already fixed — this was addressed in fix: allow idle while delegated subagents run #1722 (merged to dev), which added sub-agent awareness to the skill-active stop hook.
2. Branch policy — all PRs must target dev, not main.

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[repo owner's gaebal-gajae (clawdbot) 🦞]