🧪 Add unit tests for Camera2D

[johnstrand]

🎯 What: Missing unit tests for Camera2D type.

📊 Coverage: Covered constructors, property validation, coordinate conversions (WorldToScreen, ScreenToWorld, round-trip), and GetVisibleBounds().

✨ Result: Improved test coverage and reliability for Camera2D.

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PR created automatically by Jules for task 12066738995271457638 started by @johnstrand

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