Fix: Robust Event Hijacking for Background Play (prevents site breakage)

[biplavbarua]

Hey @polywock! 👋
I completely understand why you had to revert the "Force Background Play" feature. I dug into the issue regarding the anime websites breaking, and I found the root cause.

The Issue:
My previous implementation hijacked addEventListener to block visibility events, but didn't override removeEventListener. This meant that when sophisticated web apps (like anime sites or SPAs) tried to clean up their event listeners, they couldn't remove my wrapper. This caused memory leaks and logic errors where sites thought they were still listening to events they tried to remove.

The Fix:
I've rewritten the logic to be much more robust:

1. Symmetry: Now overrides both addEventListener and removeEventListener.
2. Tracking: It keeps a Map of original listeners to their wrappers.
3. Clean Cleanup: When a site calls removeEventListener, it correctly looks up the wrapper and removes it from the browser, ensuring no "ghost" listeners are left behind.
   This should allow the "Force Background Play" / "Prevent background detection" feature to exist safely without interfering with a site's internal logic.

Thanks again for the feedback and for maintaining this awesome extension! Hope this implementation is solid enough to be merged back in. 🚀

[polywock]

Hi! Tested and it doesn't seem to resolve the issue. You can try yourself at https://hianime.to