ADD: CSM with base shadow map

shaders/input_structures.glsl

@@ -3,10 +3,16 @@ layout(set = 0, binding = 0) uniform  SceneData{
     mat4 view;
     mat4 proj;
     mat4 viewproj;
+    // Legacy single shadow matrix (used for near range in mixed mode)
     mat4 lightViewProj;
     vec4 ambientColor;
     vec4 sunlightDirection; //w for sun power
     vec4 sunlightColor;
+
+    // Cascaded shadow matrices (0 = near/simple map, 1..N-1 = CSM)
+    mat4 lightViewProjCascades[4];
+    // View-space split distances for selecting cascades (x,y,z,w)
+    vec4 cascadeSplitsView;
 } sceneData;
 
 layout(set = 1, binding = 0) uniform GLTFMaterialData{