🎨 refactor(image-metadata): reorganize and optimize metadata handling

- Add `_type.py` for type definitions and helper functions
- Improve error handling and type checking in `lsb_extractor.py`
- Refactor `__init__.py` to use new types and helper functions
- Update `CommentModel` to use `Optional` for all fields
- Enhance `apply_to_image` to handle various input types
- Add `_extract_metadata_from_lsb` and `_extract_metadata_from_comments` methods
- Improve `verify_image_is_novelai` for better metadata extraction and verification

src/novelai_python/tool/image_metadata/__init__.py

@@ -170,7 +170,7 @@ def _extract_metadata_from_lsb(cls, image: IMAGE_INPUT_TYPE):
     def _extract_metadata_from_comments(cls, image: IMAGE_INPUT_TYPE):
         """
         Extract metadata from image comments and other info.
-        :param image: IMAGE_INPUT_TYPE
+        :param image: Union[str, bytes, Path, BytesIO]
         """
         with Image.open(image) as img:
             title = img.info.get("Title", None)