All Phase 2 deliverables (hook.rs, pty.rs, --no-inherit-hooks, mock-claude
fixture, test_pty_spawns_tty) were implemented in prior commits. All 14 unit
tests and the integration test pass. This commit records the bead close.
Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Bead-Id: bf-rw7
