Implement Alert Feature for Unsaved Changes in Editor

This pull request implements the "Better Save" feature (issue #11) by introducing an alert mechanism that warns users of unsaved changes when attempting to leave the screen without saving their content. The changes are contained within the editor.js file. **Changes**: Added a new alert feature that triggers when the user attempts to navigate away from the editor screen without saving their changes. Implemented a check to detect unsaved changes and display a confirmation prompt to the user. **Related Issues:** Closes #11: Better Save feature implementation **Notes:** This implementation uses a flag called `prevent_save` and function `checkForUnsavedChanges` to check for unsaved changes. Also added a `beforeunload` event listener to make changes to prevent_save flag based on user choice.