Vim mode: support `ciw` to change inner word

What version of Codex CLI is running?

codex-cli 0.130.0

What subscription do you have?

ChatGPT Enterprise

Which model were you using?

_No response_

What platform is your computer?

Darwin 25.3.0 arm64 arm

What terminal emulator and version are you using (if applicable)?

Ghostty 1.3.1 stable

Codex doctor report

not available

What issue are you seeing?

In Codex CLI Vim mode, ciw does not behave like Vim's "change inner word".

Expected: delete the word under the cursor and enter insert mode there.
Actual: Codex inserts a literal w on a new line / below the cursor.

What steps can reproduce the bug?

1. Open Codex CLI.
2. Enable Vim mode.
3. Type a prompt with a word, e.g. hello world.
4. Press Esc.
5. Put the cursor on world.
6. Type ciw.

Expected: world is deleted and insert mode starts at that position.
Actual: a literal w is inserted on a new line / below the cursor.

What is the expected behavior?

_No response_

Additional information

_No response_