loading fragments mostly working (not notifying anyone yet)

src/fragment_store/fragment_store_i.hpp

@@ -1,9 +1,13 @@
 #pragma once
 
+#include <entt/entity/registry.hpp>
+
 #include <cstdint>
 
 // internal id
 enum class FragmentID : uint32_t {};
+using FragmentRegistry = entt::basic_registry<FragmentID>;
+using FragmentHandle = entt::basic_handle<FragmentRegistry>;
 
 struct FragmentStoreI {
 	virtual ~FragmentStoreI(void) {}