When one task call spawns two or more live siblings with spawn capacity
and IRC enabled, TaskTool.execute appends a coordinate-via-irc
suggestion, composed onto the specialization advisory through the same
seam. Tighten the subagent COOP section and irc tool prompt so guidance
spans discovery (list who/what), coordination (message before
overlapping edits), and follow-up (replyTo/await) instead of only
assuming agents resolve collisions on their own.
Refs #2471
Op: extend
metaphorics