Dead keys break in VS Code Remote SSH terminal on Linux

What issue are you seeing?

Follow-up to #13638: dead-key accent composition can still fail inside Codex when VS Code is attached to a native Linux host through Remote SSH. The new report in https://github.com/openai/codex/issues/13638#issuecomment-4458442938 reproduces this on an aarch64 Raspberry Pi + VS Code Remote SSH session, where the escape sequence ^[[13;1:3u leaks into the terminal and dead keys such as circumflex and grave do not produce accented characters.

What steps can reproduce the bug?

1. Connect to a native Linux host through VS Code Remote SSH.
2. Open the integrated terminal on that remote host.
3. Run codex.
4. Type a dead-key combination such as circumflex or grave followed by a vowel.

What is the expected behavior?

Dead-key composition should match the same VS Code terminal outside Codex.

Additional information

The current workaround is CODEX_TUI_DISABLE_KEYBOARD_ENHANCEMENT=1 codex. The suspected follow-up is to skip crossterm keyboard enhancement flags for Linux VS Code terminals, not just the original WSL + VS Code path fixed by #18741.