fix: Use POSIX redirect in pre-commit gitleaks guard

[homin-bt]

&> /dev/null in .husky/pre-commit is a bashism. Husky runs hooks under /bin/sh, so on systems where that is dash (Linux CI runners) the guard parses as a backgrounded command -v gitleaks & followed by a bare > /dev/null redirection, whose exit status is always 0. The if is therefore always true: gitleaks protect runs even when gitleaks is not installed, and the warning branch is unreachable. This was failing on CI with Linux runners.

Verified with the dash on macOS:

$ dash -c 'if command -v nonexistent &> /dev/null; then echo then; else echo else; fi'
then          # wrong
$ dash -c 'if command -v nonexistent >/dev/null 2>&1; then echo then; else echo else; fi'
else          # correct

After the change, running the hook under dash with gitleaks absent takes the else branch and prints the intended warning.

[chatgpt-codex-connector]

Codex Review Summary

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Review	Status	Commit	Review trigger
📝 Code Review	✅ Completed 2026-09-14T18:13:33.250727Z	058ad4e	PR opened

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