feat(tui): make turn interruption keybind configurable (#24766)

## Why

Interrupting an active turn is currently fixed to `Esc`, which is easy
to hit accidentally and cannot be customized through `/keymap`. This
gives users a less accidental binding while preserving the existing
default.

## What Changed

- Adds `tui.keymap.chat.interrupt_turn` to `/keymap`, defaulting to
`esc` and supporting remapping or unbinding.
- Uses the configured interrupt binding for running-turn status, queued
steer interruption, and `request_user_input`, including the visible
hints.
- Preserves local `Esc` behavior for popups, Vim insert mode, and
`/agent` editing while validating conflicts with fixed/backtrack and
request-input navigation bindings.
- Adds behavior and snapshot coverage for remapped interruption paths.

## How to Test

1. Run Codex and open `/keymap`, then set **Interrupt Turn** to `f12`.
2. Start a turn and confirm `Esc` no longer interrupts it while `f12`
does; the running hint should display `f12 to interrupt`.
3. Queue a steer while a turn is running and confirm the preview
displays `f12`; pressing it should interrupt and submit the steer
immediately.
4. Trigger a `request_user_input` prompt and confirm its footer uses
`f12`; with notes open, `Esc` should still clear notes while `f12`
interrupts the turn.
5. Clear the Interrupt Turn binding and confirm the key-specific
interrupt hint is removed while `Ctrl+C` remains available.

Targeted validation:

- `just write-config-schema`
- `just fix -p codex-config`
- `just fix -p codex-tui`
- `just fmt`
- `just argument-comment-lint-from-source -p codex-config -p codex-tui`
- `just test -p codex-config`
- `cargo insta pending-snapshots --manifest-path tui/Cargo.toml`
- `just test -p codex-tui keymap_setup::tests`
- `just test -p codex-tui` (fails in two pre-existing guardian
feature-flag tests unrelated to this diff; the intentional picker
snapshot updates were reviewed and accepted)

codex-rs/tui/src/keymap_setup/actions.rs

@@ -93,6 +93,7 @@ pub(super) const KEYMAP_ACTIONS: &[KeymapActionDescriptor] = &[
     action("global", "Global", "toggle_vim_mode", "Turn Vim composer mode on or off."),
     gated_action("global", "Global", "toggle_fast_mode", "Turn Fast mode on or off.", KeymapActionFeature::FastMode),
     action("global", "Global", "toggle_raw_output", "Toggle raw scrollback mode."),
+    action("chat", "Chat", "interrupt_turn", "Interrupt the active turn."),
     action("chat", "Chat", "decrease_reasoning_effort", "Decrease reasoning effort."),
     action("chat", "Chat", "increase_reasoning_effort", "Increase reasoning effort."),
     action("chat", "Chat", "edit_queued_message", "Edit the most recently queued message."),
@@ -234,6 +235,7 @@ pub(super) fn binding_slot<'a>(
         ("global", "toggle_vim_mode") => Some(&mut keymap.global.toggle_vim_mode),
         ("global", "toggle_fast_mode") => Some(&mut keymap.global.toggle_fast_mode),
         ("global", "toggle_raw_output") => Some(&mut keymap.global.toggle_raw_output),
+        ("chat", "interrupt_turn") => Some(&mut keymap.chat.interrupt_turn),
         ("chat", "decrease_reasoning_effort") => Some(&mut keymap.chat.decrease_reasoning_effort),
         ("chat", "increase_reasoning_effort") => Some(&mut keymap.chat.increase_reasoning_effort),
         ("chat", "edit_queued_message") => Some(&mut keymap.chat.edit_queued_message),
@@ -357,6 +359,7 @@ pub(super) fn bindings_for_action<'a>(
         ("global", "toggle_vim_mode") => Some(runtime_keymap.app.toggle_vim_mode.as_slice()),
         ("global", "toggle_fast_mode") => Some(runtime_keymap.app.toggle_fast_mode.as_slice()),
         ("global", "toggle_raw_output") => Some(runtime_keymap.app.toggle_raw_output.as_slice()),
+        ("chat", "interrupt_turn") => Some(runtime_keymap.chat.interrupt_turn.as_slice()),
         ("chat", "decrease_reasoning_effort") => Some(runtime_keymap.chat.decrease_reasoning_effort.as_slice()),
         ("chat", "increase_reasoning_effort") => Some(runtime_keymap.chat.increase_reasoning_effort.as_slice()),
         ("chat", "edit_queued_message") => Some(runtime_keymap.chat.edit_queued_message.as_slice()),

codex-rs/tui/src/keymap_setup/picker.rs

@@ -60,6 +60,7 @@ struct KeymapContextTab {
 
 const KEYMAP_COMMON_ACTIONS: &[(&str, &str)] = &[
     ("composer", "submit"),
+    ("chat", "interrupt_turn"),
     ("editor", "insert_newline"),
     ("composer", "queue"),
     ("global", "toggle_fast_mode"),