Support Codex auto-rewriter hooks on native Windows

Summary

Codex on native Windows now appears to support hooks via .codex/hooks.json and [features].hooks = true, so RTK should consider enabling the Codex auto-rewriter path on Windows instead of keeping Windows on prompt-only AGENTS.md + RTK.md guidance.

Context

There is already related RTK work/discussion:

• #1003 asks to add hooks to Codex.
• #899 added a native Codex hook integration path, but still mentioned falling back to prompt-only setup on Windows.
• #1550 adds an official Codex deny-retry hook with rtk hook codex and rtk init --codex writing hooks/config, but it has not landed yet.

The Windows assumption seems worth revisiting. In current Codex builds, Windows can load hook entries from C:\Users\<user>\.codex\hooks.json, and the Codex settings UI shows lifecycle hooks such as PreToolUse, PostToolUse, SessionStart, UserPromptSubmit, and Stop.

I also tested another tool's Codex hook setup on native Windows. After removing one incompatible regex look-ahead from its matcher, Codex loaded and enabled its hooks. This suggests the remaining blocker is not "Windows has no hooks", but "hook config must use Codex-supported matcher syntax and Windows-safe commands".

Request

Please consider prioritizing Windows support for the Codex RTK auto-rewriter:

• rtk init --codex should write/update .codex/hooks.json or $CODEX_HOME/hooks.json on Windows when hooks are enabled.
• It should enable the current Codex feature flag, likely [features].hooks = true.
• It should avoid regex features unsupported by Codex hook matchers.
• It should use Windows-safe command invocation for rtk hook codex.
• rtk init --show should report whether the Codex hook is installed and active on Windows.
• If full input rewriting is still limited by Codex upstream behavior, a deny/retry or guidance hook would still be useful as an intermediate auto-rewriter path.

Why this matters

RTK's current Codex-on-Windows path is still prompt-level guidance through AGENTS.md + RTK.md. That works, but it is much less reliable than automatic tool interception. Since Codex Windows hooks now appear usable, RTK could provide the same kind of shell-output protection on Windows Codex that users already expect from hook-based integrations.