- Implement unit tests to cover `Image` creation, metadata management, saving/loading, and error handling.
- Add separate constructors for `Full` and `Partial` image types (`new_full`, `new_partial`).
- Introduce robust path handling methods (`metadata_dir`, `image_json_path`) for consistent metadata structure.
- Enhance error diagnostics with `InvalidPath` variant in `ImageError`.
- Update `Cargo.toml` for test module inclusion.
- Standardize formatting by aligning and cleaning up indentation, spacing, and line breaks across multiple modules.
- Enhance logging with improved message formatting for better context and readability.
- Simplify error handling in `pkg6dev`, `pkg6repo`, and core libraries by consolidating redundant patterns and improving clarity.
- Update test cases to reflect formatting and logging changes while extending coverage of edge cases.
- Perform general cleanup, including removing unused imports, refining comments, and ensuring consistent style.
