New skyboxrenderer + moved meshrenderer inside engine and out from main to clean that up

AgentData/lighting_and_skybox_plan.md

@@ -231,3 +231,62 @@ graph LR
 1. **Cubemap source** — **Procedural gradient skybox** chosen because asset loading infrastructure is not yet established.
 2. **Sampler heap** — Evaluate what exists. However, with a procedural skybox, we won't need a sampler for Phase 3! (The sky color can be procedurally generated from the reconstructed view direction).
 3. **Specular** — **Blinn-Phong** specular, structured in an agnostic way so PBR (physically based rendering) parameters can be plugged in later.
+
+---
+
+## Phase 4: Forward Rendered Entity Lights
+
+A simple, fast forward renderer using a Global Structured Buffer for entity-based point lights.
+
+### Approach: Bindless Global Lights Buffer
+
+Instead of passing each light via PushConstants, we pass a `StructuredBuffer<PointLight>` index and iterate over the active lights in the fragment shader.
+
+### New C++ Components
+
+```cpp
+struct PointLight
+{
+    Vector3 Position;
+    float   Radius;
+    Vector3 Color;
+    float   Intensity;
+};
+```
+
+1. **Lights Buffer Allocation**: Allocate a `StructuredBuffer` large enough for all potential lights (e.g., max 1024).
+2. **Buffer Upload**: Loop through the active game entity lights every frame and upload them using the TransferBuffer system.
+3. **PushData Update**:
+   - `uint32 LightsBufferIndex`
+   - `uint32 ActiveLightCount`
+
+### Shader Design
+
+**Fragment Shader Expansion** loop over all `ActiveLightCount` to compute the attenuation and diffuse, then accumulate.
+
+```hlsl
+StructuredBuffer<PointLight> lights = ResourceDescriptorHeap[LightsBufferIndex];
+
+float3 totalDiffuse = Color.rgb * LightColor * NdotL; // Include Directional Sun
+
+for (uint i = 0; i < ActiveLightCount; ++i)
+{
+    PointLight light = lights[i];
+    
+    float3 lightVector = light.Position - WorldPosition;
+    float distance = length(lightVector);
+    
+    if (distance > light.Radius) continue;
+    
+    float3 L = lightVector / distance;
+    float NdotL = saturate(dot(N, L));
+    
+    float attenuation = 1.0 - saturate(distance / light.Radius);
+    attenuation *= attenuation; // inverse square-ish 
+    
+    totalDiffuse += Color.rgb * light.Color * light.Intensity * NdotL * attenuation;
+}
+```
+
+> [!NOTE]
+> Passing `WorldPosition` to the Fragment shader from the Vertex shader is required for positional lighting.