fix(hook): reduce hook spawn overhead

[zerone0x]

Summary

• cache the rtk version guard to avoid spawning multiple processes on every hook run
• parse version in bash to remove grep/cut/head subprocesses
• reduce jq invocations by building updated input directly from the original payload

Fixes #968

Test plan

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

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

[CLAassistant]

All committers have signed the CLA.

[aeppling]

Hello,

Thanks for the contribution

Please sign the CLA above so we can merge this

[pszymkowiak]

Thanks @zerone0x — solid optimization. The version cache, herestring instead of echo|jq, and single-pass jq are all good improvements for reducing hook overhead (#968).

Two notes (non-blocking):

1. The cache file (~/.cache/rtk-hook-version-ok) has no expiry — after an rtk upgrade, the old cache persists. Consider adding the version to the filename (e.g., rtk-hook-version-ok-0.34) or clearing it on rtk init.
2. This PR modifies rtk-rewrite.sh which is also modified by PR #981 (permission model). Whichever merges first will cause a conflict on the other — just a heads-up for rebase.

LGTM.