Define PBR minimum roughness as named constant

[coderabbitai[bot]]

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Description

The recent change in PR #1351 updated the minimum roughness clamp value from 0.005 to 0.04 for the GGX microfacet model to ensure visible specular highlights. However, this magic number should be defined as a named constant to improve code maintainability and make the physical reasoning behind this value clearer.

Context

Currently in package/Shaders/Lighting.hlsl line 2108:

pbrSurfaceProperties.Roughness = clamp(rawRMAOS.x, 0.04, 1.0);

This magic number should be replaced with a descriptive named constant like PBR_MIN_ROUGHNESS.

Benefits

• Improved code readability and maintainability
• Makes the physical reasoning behind the value more explicit
• Easier to adjust if needed in the future
• Follows best practices for avoiding magic numbers

References

• PR: https://github.com/doodlum/skyrim-community-shaders/pull/1351
• Comment: https://github.com/doodlum/skyrim-community-shaders/pull/1351#discussion_r2249344753