Terminal: Handle raw mode cleanup on panic (ensure terminal restored on abnormal exit)

[exlier]

Problem

• When the shell panics, is killed, or otherwise exits while the terminal is in raw/cbreak mode, the terminal is often left unusable (no echo, broken input). Current cleanup runs on normal shutdown but not reliably on panic/unwind.

Impact

• After a crash, users must run reset or reopen a terminal session. This is high friction for developers and users, and impedes debugging.