Add new 'shallow' option to diff function that performs shallow comparison
by only comparing primitive values at the first level and ignoring nested
objects and arrays. This is useful when you only need to track changes in
top-level primitive properties without recursing into complex structures.

Changes:
- Add 'shallow' boolean option to Options interface
- Skip objects/arrays in REMOVE, CHANGE, and CREATE operations when shallow mode is enabled
- Update test data with simplified car examples instead of provider data
- Add comprehensive tests for shallow vs deep comparison modes