Review and refactor TSL node graphs for performance, clarity, and portability

Goal

Review and refactor the provided TSL TypeScript shader logic (nodes + material slots) to reduce GPU cost and improve readability without visible regressions.

For full TSL documentation refer to: https://github.com/mrdoob/three.js/wiki/Three.js-Shading-Language

Success criteria

• Visual output is indistinguishable under normal viewing (small numeric drift is acceptable).
• No feature regressions; public APIs (uniforms, exported functions, material slot assignments) remain compatible unless explicitly justified.
• Fewer or cheaper instructions in the bottleneck stage and no added texture fetches unless justified.
• Code stays in TSL (no raw GLSL strings).

Inputs

• Current TSL sources (TypeScript) and where they are bound (material slots, post-processing pass, compute).
• (Optional) Active light count, material flags, pipeline notes, target backend (WebGL2/WebGPU).