chore: downgrade msw to version 1.3.5 and update mockServiceWorker.js

- Downgraded msw dependency from 2.13.4 to 1.3.5 in package.json.
- Updated mockServiceWorker.js to reflect changes in the MSW version.
- Modified event listener methods to use `self` for consistency.
- Simplified message handling and response structure.
- Improved error handling for network errors.
- Removed unnecessary comments and unused code.