Add diagnostics for invisible creatures and update shadow signatures

- Log warning when WotLK M2 skin file is missing (causes invisible creatures)
- Move skin loading inside version >= 264 check to skip unnecessary readFile
- Update renderShadow header signatures to match implementation (shadow culling)

include/rendering/wmo_renderer.hpp

@@ -152,7 +152,8 @@ public:
     /**
      * Render depth-only for shadow casting
      */
-    void renderShadow(VkCommandBuffer cmd, const glm::mat4& lightSpaceMatrix);
+    void renderShadow(VkCommandBuffer cmd, const glm::mat4& lightSpaceMatrix,
+                      const glm::vec3& shadowCenter = glm::vec3(0), float shadowRadius = 1e9f);
 
     /**
      * Get number of loaded models