Show both session-total and segment metrics when resuming/continuing a session

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

When exiting a Claude Code session, the CLI shows useful metrics:

Total cost:            $12.34
Total duration (API):  25m 10s
Total duration (wall): 2h 15m 30s
Total code changes:    500 lines added, 80 lines removed
Usage by model:
     claude-opus-4-6:  8.0k input, 50.0k output, 15.0m cache read, 500.0k cache write ($12.20)
    claude-haiku-4-5:  100.0k input, 700 output, 0 cache read, 0 cache write ($0.14)

When you resume or continue that session (--resume or --continue), do some more work, and then exit again, the metrics shown are cumulative from the beginning of the session - not from the point you resumed.

This makes it impossible to know how much the current segment of work cost. If I resumed a $12.34 session and the exit summary shows $15.50, I have to mentally subtract to figure out that the resumed segment cost $3.16.

What Should Happen?

When exiting a resumed/continued session, show both:

1. Segment metrics - cost, duration, and usage for the current resume segment only
2. Session total metrics - cumulative totals across all segments (what is shown today)

For example:

This segment:
  Cost:            $3.16
  Duration (API):  8m 12s
  Duration (wall): 25m 3s
  Code changes:    120 lines added, 15 lines removed

Session total:
  Cost:            $15.50
  Duration (API):  33m 22s
  Duration (wall): 2h 40m 33s
  Code changes:    620 lines added, 95 lines removed

This would give users clear visibility into both the incremental cost of each work segment and the cumulative session cost.

Steps to Reproduce

1. Start a Claude Code session and do some work
2. Exit - note the metrics shown
3. Resume the session: claude --resume <session-id>
4. Do some more work
5. Exit again - the metrics shown are cumulative, with no way to see what the resumed segment alone cost

Claude Code Version

2.1.71

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)