Terminal left with mouse-tracking/focus-reporting enabled after CLI crashes #5120

Describe the bug

When Copilot CLI crashes or exits abruptly, it doesn't restore the terminal modes it enabled. The parent shell then echoes every mouse movement and focus change as raw escape sequences, which leaves the tab unusable.

PS C:\...> [555;50;35M[555;49;34M[555;48;34M[555;48;35M ... 1M[O[I[O[I[104;20m ...

These modes are left on after the process has exited:

Affected version

GitHub Copilot CLI 1.0.93

Steps to reproduce the behavior

1. Start copilot in PowerShell 7 inside Windows Terminal.
2. Use it normally until the CLI crashes or exits abruptly. This is intermittent and I don't have a reliable trigger.
3. At the PowerShell prompt, move the mouse or switch focus away from the window and back.
4. Escape sequences are typed into the prompt.

Workaround: reset the modes manually:

Write-Host -NoNewline "`e[?1000l`e[?1002l`e[?1003l`e[?1005l`e[?1006l`e[?1015l`e[?1004l"

Expected behavior

Terminal modes are restored on every exit path, including crashes, unhandled errors and forced termination, so the parent shell is left usable.

Additional context

The session's process log ends abruptly with routine INFO entries. There's no error, panic or shutdown entry, which suggests a hard crash rather than a handled exit.