[Feature] Basic Materials and Lighting System

[vmarcella]

Overview

Introduce a simple material and lighting system for lit 3D rendering, providing a foundation for more advanced shading in the future.

Scope

• Material Struct: Diffuse color, optional diffuse texture, basic properties (e.g., shininess)
• Light Types: Directional light (sun-like) and/or point light
• Lit Shaders: Fragment shaders implementing basic diffuse/specular lighting (e.g., Blinn-Phong)
• Light Uniform Buffers: Bind group layout for passing light data to shaders

Motivation

Current rendering is unlit. Adding basic lighting enables more visually appealing 3D scenes and establishes patterns for future PBR or advanced lighting features.

Acceptance Criteria

• Material struct with color and optional texture
• At least one light type (DirectionalLight or PointLight)
• Shader support for basic diffuse lighting
• Uniform buffer integration for light parameters
• Example demonstrating a lit scene with materials
• Documentation for material and lighting APIs