## Why
Plan mode questionnaires reuse the shared composer for free-form
answers, but the surrounding `request_user_input` overlay still treated
every `KeyCode::Enter` as “advance to the next question.” That made
`Shift+Enter` insert a newline in the composer and then immediately
advance the questionnaire anyway.
Fixes#23448.
## What Changed
- pass the live `RuntimeKeymap` into `RequestUserInputOverlay` so its
embedded composer honors existing `/keymap` composer/editor remaps
- advance free-form questions only on the configured composer submit
binding, instead of any Enter-shaped key event
- add regressions for `Shift+Enter` newline behavior and configured
composer submit bindings inside the questionnaire UI
## How to Test
1. Start Codex in Plan mode and trigger a `request_user_input`
questionnaire with a free-form answer field.
2. Focus the free-form field, type a line, then press `Shift+Enter`.
3. Confirm the answer gains a newline and the questionnaire stays on the
same question.
4. Press the configured submit binding, or plain `Enter` with the
default keymap, and confirm the questionnaire advances as before.
Targeted tests:
- `cargo test -p codex-tui
bottom_pane::request_user_input::tests::freeform_ -- --nocapture`
## Notes
- `cargo test -p codex-tui` still reaches an unrelated existing stack
overflow in
`app::tests::discard_side_thread_removes_agent_navigation_entry` on this
checkout.
- `just argument-comment-lint` is locally blocked by Bazel analysis
failing in external `compiler-rt` before the lint runs.