debug: hardcoded light in fragment shader — no UBO light data

Light at (0,10,0) hardcoded in GLSL. Tests if lighting math works.
If light works: problem is UBO layout for light data (std140 padding).
If artifacts: problem is in fragWorldPos or fragNormal.

src/Engine.Graphics.Vulkan/Shaders/triangle.frag

@@ -8,22 +8,23 @@ layout(location = 0) out vec4 outColor;
 
 layout(set = 0, binding = 0) uniform CameraUBO {
     mat4 vp;
-    vec4 pointLightPos;
-    vec4 pointLightColor;
 };
 
 void main()
 {
     vec3 N = normalize(fragNormal);
-    vec3 toLight = pointLightPos.xyz - fragWorldPos;
+    
+    // Hardcoded light at (0, 10, 0) — test if lighting works at all
+    vec3 lightPos = vec3(0.0, 10.0, 0.0);
+    vec3 toLight = lightPos - fragWorldPos;
     float dist = length(toLight);
     vec3 L = normalize(toLight);
 
     float NdotL = max(dot(N, L), 0.0);
     float atten = 1.0 / (1.0 + dist * dist * 0.05);
-    float intensity = pointLightPos.w;
+    float intensity = 30.0;
 
-    vec3 color = fragAlbedo * pointLightColor.xyz * NdotL * intensity * atten;
+    vec3 color = fragAlbedo * vec3(1.0, 0.9, 0.7) * NdotL * intensity * atten;
     color += fragAlbedo * 0.02;
 
     outColor = vec4(color, 1.0);