- Introduce newGrokClient and gitRun vars to allow mocking in tests.
- Refactor commit, commitmsg, history, prdescribe, and review cmds into separate run funcs.
- Update docs, lint, and review to use newGrokClient.
- Add comprehensive unit tests in run_test.go covering happy paths, errors, and edge cases.
- Expand grok client tests with SSE server mocks for Stream* methods.