Add EasyEffects Presets plugin

[nerdyworm]

Summary

• Add EasyEffects Presets to the Okomart catalog.
• The plugin switches EasyEffects output presets from the Omarchy bar.
• The plugin is published as a standalone public repository.

Plugin repository: https://github.com/nerdyworm/omarchy-easyeffects-presets

Checks

• Omarchy plugin validation passed for Okomart.
• Omarchy plugin validation passed for the standalone plugin.
• The catalog generator completed successfully.
• The full Okomart test suite passed.
• A clean interactive install from the public Git URL passed without a shell restart.
• The preset panel, preset selection, and preset cycling were tested in the current Omarchy shell.