[FEATURE] Agents view: show when each session last worked instead of how long it worked

Feature request

In the claude agents view, the third line of each session row shows how long the session has worked (a duration).

When supervising several agents, the more useful fact is when the session last worked: the time of its last activity, shown as a relative time ("5m ago", "2h ago") or a clock time.

Proposal

• Show last-activity time on that line instead of the duration, or
• Make the line configurable (duration / last active / both), e.g. via a settings.json key.

Why

• With many agents, the questions are "which one moved recently?" and "which one has been idle since yesterday?". A duration answers neither.
• A session that worked 3 minutes an hour ago and one that worked 3 minutes a day ago look identical today.

Related

• #72746: the view's "last changed" time comes from transcript file mtime, not conversation activity. A last-active display should use the last timestamped conversation record, as that issue suggests.

Environment

• Claude Code 2.1.283
• Linux, claude agents run in the VS Code integrated terminal