fix(tui): cannot type into custom answer input in question prompts

[ziuus]

Description

When a question prompt offers "Type your own answer" (custom answer option), selecting it with arrow keys + Enter opens the input but it locks / cannot be typed into. Typing does nothing or the edit immediately exits. Reproducible in the TUI and in CLI direct/run mode question prompts.

Steps to reproduce

1. Trigger any question tool call that has a "Type your own answer" option.
2. Arrow down to the custom option and press Enter.
3. Try to type — characters are not registered or the edit exits immediately.

Expected behavior

After selecting the custom option, the text input keeps focus and accepts typing until Enter is pressed to save.

Actual behavior

The input locks up / can't be typed into, or the edit mode immediately closes.

[github-actions]

This issue might be a duplicate of existing issues. Please check:

• TUI: cannot submit a custom "Type your own answer" in question/ask prompt (Enter swallowed by focused textarea) #30393: Same bug — selecting "Type your own answer" in a question prompt opens the input but it cannot be typed into / Enter is swallowed, making the custom answer path non-functional. That issue also includes a root cause analysis and suggested fix.

Please review #30393 and consider whether your report adds new information (e.g. a different code path or symptom). If so, it would be helpful to add that context there.

[ziuus]

Closing as duplicate of #30393, which is the canonical report for this bug. The fix is submitted in PR #41517.