chore: upgrade prettier to v3 (#644)

## Description

This PR addresses the following improvements:

**Unify Prettier Version**: Currently, the Prettier version used in
`/package.json` and `/codex-cli/package.json` are different. In this PR,
we're updating both to use Prettier v3.

- Prettier v3 introduces improved support for JavaScript and TypeScript.
(e.g. the formatting scenario shown in the image below. This is more
aligned with the TypeScript indentation standard).

<img width="1126" alt="image"
src="https://github.com/user-attachments/assets/6e237eb8-4553-4574-b336-ed9561c55370"
/>

**Add Prettier Auto-Formatting in lint-staged**: We've added a step to
automatically run prettier --write on JavaScript and TypeScript files as
part of the lint-staged process, before the ESLint checks.

- This will help ensure that all committed code is properly formatted
according to the project's Prettier configuration.

package.json

@@ -38,6 +38,7 @@
     "*.md": "prettier --write",
     ".github/workflows/*.yml": "prettier --write",
     "**/*.{js,ts,tsx}": [
+      "prettier --write",
       "pnpm --filter @openai/codex run lint",
       "cd codex-cli && pnpm run typecheck"
     ]