hive-subagent-mcp already stamps a subagent=<name> resource attribute
(alongside the parent's own agent=<name>) on every claude_code.* sample
a spawned subagent turn emits -- the label already existed, it just
wasn't plotted anywhere. Adds five panels: subagent cost, subagent
turns, subagent cost share (of all cost), cost by subagent name, and
cost by parent agent. No backend changes needed.
8464e50f3a