[💄Feature]: Separate code from data.

[wiseaidev]

👶 Getting Started
Please search the history to see if an issue already exists for the same problem.

• I have searched the existing issues.
• I have tested the latest version.

📝 Describe the feature
The popup.js file is quite messy, containing a blend of data, code, and CSS. It would be better to apply separation of concerns and things of that nature, for the long-term maintainability.

📸 Screenshots
N/A

🔦 Context

For example, the following object could be stored in a json file under the data folder, and load it with fetch, like what I did in tts:

https://github.com/wiseaidev/flexify/blob/1b82d3c65f224f8ada93c183ed682cff3315f6c5/scripts/popup.js#L440-L542

https://github.com/wiseaidev/flexify/blob/1b82d3c65f224f8ada93c183ed682cff3315f6c5/scripts/text-to-speech.js#L17-L21