chore: Add Firefox (Gecko) Support

[Zayan-Mohamed]

Description

Currently, the extension is optimized for Chrome (Manifest V3). We need to ensure it runs smoothly on Firefox.

The Problem

Firefox handles Manifest V3 background scripts differently than Chrome (Service Workers vs Event Pages).

Tasks

1. Test the current build in Firefox (Load Temporary Add-on).
2. Identify any console errors.
3. If necessary, create a separate manifest.firefox.json or a build script that adapts the manifest for Firefox.

Difficulty: Intermediate