feat(osd): add configurable cooldown for media (now playing) popups

[Qaaxaap]

Summary

Add a configurable cooldown time to the media (now playing) OSD.

Motivation

As mentioned by users in #4070, due to some player implementation issues, OSD messages repeatedly appear when fast-forwarding. Adding a cooldown reduces unnecessary popups.

Type of Change

• Bug fix
• New feature
• Breaking change
• Refactoring
• Build / packaging

Related Issue

Closes #4070

Testing

Since I couldn't find a similar player, I quickly switched songs to test and observe, and the cooldown was correct.

Manual Coverage

• Tested on Niri
• Tested on Hyprland
• Tested on Sway
• Tested on another compositor:
• Tested with different bar positions and density settings
• Tested at different interface scaling values
• Tested with multiple monitors

Screenshots / Videos

Checklist

• This PR is ready for review, or it is marked as Draft.
• I read and followed the relevant guidance in CONTRIBUTING.md.
• I ran just format with clang-format v22+ installed, or this PR has no code changes.
• I ran the relevant build or test commands, or explained why they were not run.
• I self-reviewed the changes.
• I checked for new warnings or errors.
• I will update end-user documentation after merge, or this PR does not change user-facing configuration or behavior.
• I added or updated assets/translations/en.json, or this PR adds no new user-facing strings.
• I did not edit non-English translation files unless this PR is explicitly for translation tooling, an import/export sync, or a maintainer-requested locale change.
• I used the existing canonical names for config keys, IPC names, paths, and identifiers.

Additional Notes

I am not a native English speaker and used LLM-assisted translation