feat(hooks): add Codex hook

[maxdestors]

Summary

• Adds Codex hook

Because Codex only supports allow, we auto-allow only simple, read-only commands from a fixed whitelist:

• git / yadm: status, log, diff, show
• cat, head, tail, ls, tree, grep, wc

Everything else falls back to Codex’s native approval flow.

Partially closes #1003 and checked the work on #1550.

More work needs to be done once Codex support full rewriting.

Test plan

• cargo fmt --all && cargo clippy --all-targets && cargo test
• Manual testing: rtk <command> output inspected

I also installed it in my current WSL vscode setup and it works well. The hook must be trusted.
Also to have rtk gain --history show the commands you have to add thoses lines to ~/.codex/config.toml :

sandbox_mode = "workspace-write"

[sandbox_workspace_write]
writable_roots = ["/home/maxou/.local/share/rtk"]

Important: All PRs must target the develop branch (not master).
See CONTRIBUTING.md for details.

[CLAassistant]

All committers have signed the CLA.

[Hikarea]

I asked Codex to do this globally, for old and new chats; it worked:

rtk gain
RTK Token Savings (Global Scope)
════════════════════════════════════════════════════════════

Total commands: 858
Input tokens: 3.8M
Output tokens: 761.0K
Tokens saved: 3.1M (80.2%)
Total exec time: 77m55s (avg 5.4s)
Efficiency meter: ███████████████████░░░░░ 80.2%

By Command
───────────────────────────────────────────────────────────────────────

Command Count Saved Avg% Time Impact

───────────────────────────────────────────────────────────────────────

1. rtk rg 182 3.0M 23.9% 485ms ██████████
2. rtk git diff -- packa... 1 17.3K 76.6% 547ms ░░░░░░░░░░
3. rtk find 11 4.3K 47.0% 50ms ░░░░░░░░░░
4. rtk git diff -- app/a... 1 1.5K 27.7% 450ms ░░░░░░░░░░
5. rtk git diff -- app/a... 1 1.4K 20.0% 186ms ░░░░░░░░░░
6. rtk git diff -- app/a... 2 1.4K 15.1% 164ms ░░░░░░░░░░
7. rtk git diff -- app/a... 1 1.3K 39.1% 299ms ░░░░░░░░░░
8. rtk git diff -- app/a... 1 939 19.2% 298ms ░░░░░░░░░░
9. rtk git diff -- app/a... 1 925 19.8% 225ms ░░░░░░░░░░
10. rtk git diff -- app/a... 1 914 20.8% 183ms ░░░░░░░░░░
    ───────────────────────────────────────────────────────────────────────
    Top 10 command categories shown; 656 lower-impact command(s) omitted.