tool_call_count was inaccurate in two ways:
1. Under-counting: an assistant message with N parallel tool calls
(e.g. "kill the light and shut off the fan" = 2 ha_call_service)
only incremented tool_call_count by 1 instead of N.
2. Over-counting: tool response messages (role=tool) also incremented
tool_call_count, double-counting every tool interaction.
Combined: 2 parallel tool calls produced tool_call_count=3 (1 from
assistant + 2 from tool responses) instead of the correct value of 2.
Fix: only count from assistant messages with tool_calls, incrementing
by len(tool_calls) to handle parallel calls correctly. Tool response
messages no longer affect tool_call_count.
This impacts /insights and /usage accuracy for sessions with tool use.
3b43f7267a