Transcript viewer: add feedback after saving with 's' — currently looks half-broken

Summary

In the transcript viewer (Ctrl+R), pressing s to save the transcript produces no visible feedback. The viewer just sits there afterwards, which makes it feel like the save didn't work — or like the UI is in a half-broken state.

Current behavior

1. Open the transcript viewer
2. Press s to save
3. …nothing visibly changes

There's no confirmation that the save succeeded, no indication of where the file was written, and no hint about what to do next.

Expected / requested behavior

After saving, the viewer should at minimum show a brief confirmation. Ideally it would include:

• A clear success indicator (e.g. ✓ Saved)
• The absolute path the transcript was written to
• Optionally: file size, or a hint like "press o to open" / "copied path to clipboard"

A transient status line at the bottom of the viewer (that clears after a few seconds or on next keypress) would be enough — the key thing is that the user gets some acknowledgement that the action landed, rather than silence.

Why it matters

The current silent-on-success behavior is a small UX cut but a repeated one: every time you save a transcript, you're left wondering whether it worked, and you end up dropping to a shell to ls the output directory to confirm. A one-line confirmation removes that friction entirely.

Environment

• Claude Code CLI
• macOS (Darwin 23.4.0)