Create comprehensive documentation for orphaned process verification
system at docs/test-hygiene/orphaned-process-verification.md
The documentation includes:
- Overview of orphaned process verification and why it matters
- Usage instructions for scripts/check-orphaned-processes.sh
- Verification methods (shell script, Rust helpers, CI integration)
- Best practices for RAII guards and process cleanup
- CI integration examples
- Troubleshooting guide
Closes bf-1lghw6. Verification: notes/bf-1lghw6.md