fix: prevent resource leaks in mouse event handling

[2mawi2]

This PR fixes a resource leak in the mouse event handling code that could cause input lag over time.
This should fix #111

Changes:

• Added proper cleanup of Core Foundation objects in unregisterMouseCallback
• Release event tap and run loop source when unregistering callbacks
• Maintain proper order of operations: disable tap → remove source → release resources

Technical Details:
The fix addresses the ownership of Core Foundation objects created with CGEventTapCreate and CFMachPortCreateRunLoopSource. These functions return objects with +1 retain count that need to be properly released to prevent resource leaks.

Impact:
This should prevent the accumulation of unused event taps and run loop sources when listeners are restarted (e.g. after sleep/wake cycles), improving long-term performance and preventing potential input lag.

[artginzburg]

I spent some time profiling this. It appears that no new memory leaks were introduced, and no memory leaks were removed.

Anyway, it's a nice improvement to the code, makes it more concise. I hope we can keep it up. Going to merge this a bit later after discussing another approach in #111