feat: add Codex PreToolUse hook integration

[T0UGH]

Summary

• add rtk hook codex for Codex PreToolUse JSON payloads
• return permissionDecision: "allow" with updatedInput.command for transparent shell command rewrites
• install the hook into Codex hooks.json, preserve third-party hooks, and migrate legacy RTK Claude/shell hook entries
• keep AGENTS.md/RTK.md fallback guidance and update docs to mark Codex as a full hook integration
• suppress telemetry/hook health noise for rtk hook ... subcommands so hook stdout stays machine-readable

Verification

• /opt/homebrew/bin/cargo fmt --check
• /opt/homebrew/bin/cargo check
• /opt/homebrew/bin/cargo test --all
• /opt/homebrew/bin/cargo clippy --all-targets
• printf '%s' '{"hook_event_name":"PreToolUse","tool_name":"Bash","tool_input":{"command":"git status"}}' | /opt/homebrew/bin/cargo run --quiet -- hook codex\n

[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.
_{You have signed the CLA already but the status is still pending? Let us recheck it.}

[costleya]

https://github.com/rtk-ai/rtk/tree/develop/src/hooks

• hook_check.rs is not updated
• integrity.rs is not updated

Both of these seem to be required for the hook install to work. Was this PR tested?

[KuSh]

Thanks for this work. Codex PreToolUse support landed on develop with #3552 (merged 2026-09-13): rtk hook codex rewrites through updatedInput, and rtk init --codex installs, reports and removes the hook in hooks.json while keeping other hooks. The hook command, installer and docs this PR adds are already covered there. Develop does not remove a legacy rtk hook claude or rtk-rewrite.sh entry that is already in Codex hooks.json, which this PR did; an issue or a narrow PR against src/hooks/init/codex.rs would be welcome. rtk hook subcommands also still run the daily telemetry ping and hook-status warning in src/main.rs, which this PR skipped; that could be a small separate PR too. If I missed something this PR covers, please comment or reopen.