Bug: CLI crashes with SIGTERM on large repos

When running codex on a large monorepo (50k+ files), the CLI receives SIGTERM after ~30 seconds and exits with code 143.

Steps to reproduce:

1. Clone a large repo (e.g., kubernetes/kubernetes)
2. Run codex exec "list all go files"
3. After ~30 seconds, process is killed

Expected: Process completes or shows a timeout message
Actual: Silently killed with SIGTERM

Environment:

• codex 1.0.2
• macOS 14.5
• 16GB RAM

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