Move duplicated processExists function to shared util package: - Create internal/util/process.go with ProcessExists function - Add internal/util/process_test.go with basic tests - Update witness/manager.go to use util.ProcessExists - Update refinery/manager.go to use util.ProcessExists - Remove local processExists functions from both files 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>