Tolerate tmux lookup delays on loaded Macs

[mgc26]

Summary

• raise both tmux identity lookup ceilings from two seconds to five seconds
• preserve the existing fail-open hook behavior while avoiding identity fallback on a loaded Mac

Root cause

The public-release fresh-clone gate reproduced three failures in which a trivial tmux shim did not receive CPU time before the two-second child-process timeout. Claude events then lost their control target, while Codex events fell back to a cwd-derived identity and could split one session across two files.

Validation

• affected Claude and Codex hook suites: 50/50 passed
• full suite: 381/381 passed on the installed runtime
• full suite and TypeScript build: 381/381 passed on Node 22.18.0
• full suite and TypeScript build: 381/381 passed on Node 24.18.1
• npm audit: 0 vulnerabilities