🧪 Add unit tests for Polygon2D and Contains edge cases

[johnstrand]

🎯 What: Added comprehensive unit test suite in Polygon2DTests.cs to test Polygon2D functionality and edge cases in Polygon2D.Contains(Vector2), along with adding a bounding box early exit check in Polygon2D.Contains.

📊 Coverage: Covered constructors (including sorting clockwise and preserving vertex order), empty vertex exception, Contains for points outside bounding box, points inside bounding box but outside polygon, points inside polygon, raycast intersecting directly at vertices, concave polygons, translation via TranslateBy, and intersection overloads for polygons and lines.

✨ Result: Improved test reliability and coverage for 2D polygon geometry operations across the codebase.

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PR created automatically by Jules for task 14525086435993375639 started by @johnstrand

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