Improve request_user_input elicitation forms

[OldKrab]

Summary

Update the ACP form emitted for Codex request_user_input and align its custom-answer behavior with the native Codex CLI.

ACP request structure

For each question:

• Use the full question as the property title.
• Use the short header as the property description.
• Include the primary property in the schema required array.
• Omit empty option descriptions.

For questions where isOther is true and the options list is non-empty:

• Add None of the above to oneOf, matching the option that Codex CLI adds under the same condition.
• Replace the optional <question_id>__other property with <question_id>_note. The note is modeled as additional input associated with the selected option rather than as a replacement for that option.
• Mark the note property with _meta.codex.role: user_note instead of isOtherAnswer: true.

The top-level elicitation message is now the stable Codex needs your input to continue. text.

ACP response mapping

Codex CLI preserves the selected option and appends a non-empty note as a separate user_note: <text> answer. This adapter now returns the ACP form response in that same Codex-compatible shape instead of replacing the selected option with the custom text.

For example, selecting None of the above and entering a custom answer produces:

{
  "answers": {
    "<question_id>": {
      "answers": [
        "None of the above",
        "user_note: <custom answer>"
      ]
    }
  }
}

The <question_id>_note property is the ACP form representation used to collect the note. The None of the above option and the returned selection-plus-note answer list mirror Codex CLI behavior.