Subagent and workflow token counts skip unmetered messages

What

A subagent is a helper Claude starts to work on part of a task. Some of Claude's messages are now marked isUnmetered, meaning they are not counted as billed usage. Token counts now leave those messages out:

• Subagent results: the usage and total_tokens reported when a subagent finishes now come from the last assistant message not marked isUnmetered, instead of the final message.
• Subagent progress: the line showing tool-use count and tokens while a subagent runs now takes usage from the last message not marked isUnmetered.
• Workflow agents: in workflow agent() runs, both the running token count and the final count skip usage from messages marked isUnmetered.

Why

Token numbers for subagents and workflows should reflect billed usage, and the counter should no longer jump or drop to zero when an unmetered message happens to be the last one.