Add Vim buffer jump motions (#40958)

## What changed

- Add `gg` and `G` motions to jump to the first and last buffer lines.
- Support the motions with delete, change, and yank operators, including dot-repeat for edits.
- Expose normal-mode and operator-motion bindings in the configurable keymap while preserving conflicting user bindings.

## Testing

- Cover buffer jumps, operator combinations, repeat behavior, chord routing, and custom remapping.

GitOrigin-RevId: 24a9178cf7964053aaf9a8cd268c5434dda0778e

codex-rs/tui/src/app/tests/key_chords.rs

@@ -60,6 +60,38 @@ fn ctrl(ch: char) -> KeyEvent {
     KeyEvent::new(KeyCode::Char(ch), KeyModifiers::CONTROL)
 }
 
+#[tokio::test]
+async fn vim_buffer_jumps_route_default_chords_in_normal_and_operator_contexts() -> Result<()> {
+    for (input, command, expected) in [
+        ("one\ntwo\nthree", "gg", "!one\ntwo\nthree"),
+        ("one\ntwo\nthree", "dgg", "!"),
+        ("ag bg", "0fg", "a!g bg"),
+        ("ag bg", "0dfg", "! bg"),
+    ] {
+        let (mut app, mut tui, mut app_server) = chord_app().await?;
+        app.chat_widget.toggle_vim_mode_and_notify();
+        app.chat_widget.insert_str(input);
+
+        for (index, key) in command.chars().enumerate() {
+            press(
+                &mut app,
+                &mut tui,
+                &mut app_server,
+                KeyCode::Char(key).into(),
+            )
+            .await?;
+            if key == 'g' && index + 1 < command.len() {
+                assert!(app.key_chord_matcher.is_pending());
+            }
+        }
+
+        assert!(!app.key_chord_matcher.is_pending());
+        app.chat_widget.insert_str("!");
+        assert_eq!(app.chat_widget.composer_text_with_pending(), expected);
+    }
+    Ok(())
+}
+
 #[tokio::test]
 async fn completed_global_chord_reuses_the_existing_action_handler() -> Result<()> {
     let (mut app, mut tui, mut app_server) = chord_app().await?;