feat: basic shadow map + renderdoc labels

destrum/assets_src/shaders/scene_data.glsl

@@ -33,7 +33,12 @@ layout (buffer_reference, scalar) readonly buffer SceneDataBuffer {
     uint numLights;
     uint tileCountX;
     uint debugLightHeatmap;
+
+    // directional shadows
+    uint shadowMapId;
+    float shadowNormalOffset;
     uint padding;
+    mat4 lightViewProj;
 } sceneDataBuffer;
 
 #endif // SCENE_DATA_GLSL