Extract shared image utilities to reduce duplication

[adamtheturtle]

Move the _ImageType type alias and _get_image_data function to a new shared _image_utils module. Both vws.py and query.py previously contained identical definitions. Now both modules import from the shared utility module using local aliases to maintain their existing internal APIs.

This eliminates duplicate code while keeping the public interface unchanged.

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Note

Low Risk
Pure refactor to eliminate duplicated helper code; behavior should be unchanged aside from any unintended import/typing edge cases.

Overview
Adds a new shared module vws/_image_utils.py containing ImageType and get_image_data for reading image bytes while preserving file pointer position.

Removes the duplicated _ImageType and _get_image_data definitions from vws.py and query.py, replacing them with imports aliased to the previous internal names to keep call sites unchanged.

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