Feature: Show wall-clock timestamp alongside "Baked for" duration

Preflight Checklist

• [x] I have searched existing requests and this feature hasn't been requested yet
• [x] This is a single feature request (not multiple features)

Problem Statement

The ✻ Baked for 1h 3m 49s indicator shows how long a session took, but not when it ended. When reviewing terminal history or scrollback, it's impossible to tell what time a conversation actually completed.

Proposed Solution

Add a wall-clock timestamp next to the duration, e.g.:

✻ Baked for 1h 3m 49s @ 14:32

Or make the format configurable so users can choose to display the timestamp.

Alternative Solutions

• Using a Stop hook to print the time — but hook output doesn't appear in the terminal UI
• External notification (Slack/Lark) workaround works for push notifications, but doesn't help when reading terminal history directly

Priority

Low - Nice to have

Feature Category

Other

Use Case Example

1. Running multiple Claude Code sessions throughout the day
2. Reviewing terminal scrollback later to find when a specific task finished
3. Correlating Claude Code sessions with other events (deploys, commits, incidents, etc.)
4. Currently have to cross-reference with external notification timestamps to figure out when something completed

Additional Context

Related: #17481 (request to disable timing info entirely). This is the opposite direction — keeping the timing info but making it more useful by adding an absolute timestamp.