[Feature] Implement Light Uniform Buffer System in LitForwardLane

[eraflo]

Implement full GPU lighting integration in LitForwardLane:

Create LightingUniforms GPU-compatible struct (directional, point, spot lights)
Create light uniform buffer during lane init
Create bind group layout and bind group for lights (group 3)
Update uniform buffer each frame with extracted light data from RenderWorld
Bind light bind group during render pass
Depends on: #178 (RenderLane Resource Ownership)