- Introduce tests for chat history file handling, loading/saving, and error cases in cmd/chat_test.go
- Add tests for removeLastModifiedComments in cmd/edit_helper_test.go
- Add comprehensive tests for CleanCodeResponse in internal/grok/cleancode_test.go
- Update Makefile to centralize build artifacts in build/ directory for coverage reports and binary
- Adjust .gitignore to ignore chat_history.json and remove obsolete coverage file entries
