Use smart pointers correctly

I need to replace raw new/delete with smart pointers in this module so ownership is explicit. Convert the ResourceManager constructor and destructor to use unique_ptr for owned resources and shared_ptr where ownership is shared across systems. Before I commit, check that copy and move semantics are correct and there are no manual deletes left. Target branch is feature/smart-ptrs, reviewers: Lina and Marco, deadline Friday.

Before I push this change to the game loop, make ownership obvious for reviewers: put a short note at the top of ResourceManager explaining who owns each pointer, move the longest-lived objects into unique_ptr, expose only weak_ptr for observers, surface the one place that needed shared_ptr and why. Flag any functions that still accept raw pointers and explain the risk to a code reviewer.

I just converted several raw pointers to shared_ptr and the frame rate dropped in the profiler. The team is Alex on rendering and Priya on audio; I'm worried I introduced unexpected reference cycles or heavy copying. I cannot tell whether the slowdown is from reference-count overhead, a cycle keeping large objects alive, or extra copies in message passing. What is the most likely cause and the fastest way to diagnose and fix it?

Over the last three projects we keep reverting pointer changes after subtle crashes or leaking tests. I waste time tracing ownership and fear introducing cycles when I try to make ownership explicit. Where am I consistently losing time and credibility, and what single habit should I form to stop this? Prefer a concrete rule I can apply in code reviews and one checklist item for PRs.