* Fix Vec3/AABB pool reset logic
* resetPool()/clearPool() now reset poolPointer to 0
* Prevents endless pool growth, invalid temporary references,
and increasing memory usage
* Resolves the leaderboard-related crash mentioned in
Windows64_Minecraft.cpp
* Properly free old screens in Minecraft::setScreen()
* Added virtual destructor to Screen
* Screen destructor now cleans up GuiParticles and Buttons
* Previous screen is now deleted after screen transitions
* Screen::init() now clears old buttons/particles before re-init
* Fix GuiParticles memory leak
* Removed GuiParticle instances are now deleted in tick()
* Added GuiParticles destructor to free remaining particles
