Add /multitask command for Codex subagents

What variant of Codex are you using?

CLI and IDE Extension

What feature would you like to see?

Please add a native /multitask command to Codex CLI and IDE Extension.

Codex already supports subagents, but there is no simple built-in command like Cursor's multitask.

Example:

/multitask Implement a feature, explore the codebase, add tests, and review the final diff.

Expected behavior:

• spawn several subagents in parallel
• one agent explores the codebase
• one agent implements the change
• one agent writes or updates tests
• one agent reviews the final diff
• Codex returns one final summary

Suggested modes:

• /multitask --plan
• /multitask --implement
• /multitask --review

This would make subagents much easier to use. Right now users need to write long prompts every time, or create local custom prompts.

The feature already exists conceptually through subagents, but it needs a simple UX command.

Additional information

_No response_