Fix: Proxy setup failure handling across scripts:
- Improved error messaging in options.js
- Added 'proxyFailed' message handler in background.js
- Updated UI toggle state in popup.js when proxy fails
Enhancements for Proxy Check and "Save & Enable" Button:
- Changed the endpoint for proxy checks to 'https://check.en.anyone.tech'.
- Implemented disabling of the "Save & Enable" button during the proxy check to prevent multiple submissions.
- Updated the URL in store.js from 'store.debros' to 'dapps.debros' for the dApp Store.
