claude-code: add timeout to session-start hook

[MuskanPaliwal]

refs #1065

adds Claude Code native hook timeout to the production SessionStart hook. This makes Claude Code fail open if launching entire hooks claude-code session-start stalls before the entire process reaches Go code.

the reported hang is not specific to hook stdin parsing or the session-start handler: entire --version can also hang in the affected environment, and the sample shows the process stuck in _dyld_start. That means Cobra, hook parsing, logging, and any internal Go timeout have not started yet.

code changes

• adds optional timeout support to Claude Code hook entries.
• installs production Claude Code SessionStart hooks with timeout: 5.
• backfills timeout: 5 onto existing Entire-owned production SessionStart hooks when hooks are reinstalled.
• leaves local-dev hook installs unchanged.

why this approach

because the failure can happen before Go main() starts, the timeout needs to live outside the child entire process. Claude Code per-hook timeout is the right boundary: it can cancel the stalled hook launch and continue startup instead of waiting indefinitely.

this keeps the mitigation small and avoids adding a separate shell watchdog or changing the hook command shape.

test plan

• go test ./cmd/entire/cli/agent/claudecode
• go test ./cmd/entire/cli/agent/...
• mise run lint

release notes

• breaking changes: None.
• version impact: patch-level bug fix.
• rollout notes: fresh installs get the timeout immediately; existing users get it when Claude Code hooks are reinstalled or refreshed.

[claude]

Claude Code Review

This pull request is from a fork — automated review is disabled. A repository maintainer can comment @claude review to run a one-time review.