[fix] Properly disable the model switcher instead of just hiding it

[NextDev65]

When the model switcher is turned off in the settings, the script should do more than just hide the UI element.
It needs to completely disable the functionality by:

• Restoring the default window.fetch behavior to prevent the model from being overridden in requests.
• Potentially removing the <select> element and its associated event listeners from the DOM, rather than just setting display: none.