Fix black triangle rendering issue on goblet.3ds and broom.3ds

[moonwho101]

Updated CalculateVertNormalAndTangent, Compute3DSModelNormals, ComputeMD2ModelNormals, ComputeObDataNormals, ObjectToD3DVertList, PlayerToD3DVertList, and PlayerToD3DIndexedVertList in src/ProcessModel.cpp to handle zero-length normals and tangents for degenerate faces/UVs gracefully by providing valid unit fallback vectors. This prevents NaN and zero-vector generation during DirectXMath transformations, fixing the black triangle rendering artifacts on models such as goblet.3ds and broom.3DS.

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PR created automatically by Jules for task 14733320370972258639 started by @moonwho101

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