Regression: exit summary not shown after upgrading to 1.0.74 / 1.0.75

## Summary
After upgrading from `1.0.73` to `1.0.74` (and still broken in `1.0.75`), the CLI no longer prints the session/exit summary when quitting. Rolling back to `1.0.73` restores the expected behavior.

## Environment
- Copilot CLI: broken on `1.0.74` and `1.0.75`; works on `1.0.73` (current rollback)
- OS: Ubuntu 22.04.5 LTS on WSL2 (kernel `6.18.33.1-microsoft-standard-WSL2`)
- Terminal: `xterm-256color`
- Shell: `/bin/bash`
- `TERM=xterm-256color`

## Steps to reproduce
1. Run `copilot` (interactive mode).
2. Have a normal conversation.
3. Exit via `/exit` (also tried `ctrl+d`).
4. Observe: no summary is printed on exit.

## Expected behavior
On exit, the CLI prints a session summary (as it does in `1.0.73`).

## Notes
- `/exit print` still force-prints the session content, but the normal automatic summary on exit is missing.
- Verified on both `1.0.74` and `1.0.75` before rolling back to `1.0.73`.
- No relevant setting in `settings.json` appears to gate this (`showTimestamps`, footer settings, etc. were checked).

## Regression range
First bad: `1.0.74` — Last good: `1.0.73`

Riproduci la regressione eseguendo la copilot CLI interattiva e uscendo con /exit o ctrl+d, quindi confronta il comportamento tra 1.0.73 e 1.0.74. Segui il normale percorso di uscita invece del comando /exit di stampa; il lavoro è completato quando il riepilogo automatico della sessione viene restituito all’uscita senza interrompere il comportamento esistente di stampa forzata.

Scritto dal modello di indicizzazione a partire dal testo della issue.