UTF-8-Safe Base64 Converter: Overcoming Browser Limitations with File Support

The browser's native btoa() and atob() functions fail on Unicode characters outside Latin-1, a critical gap for developers handling UTF-8 text, attachments, and data URLs. This Next.js implementation leverages encodeURIComponent and FileReader to bypass that constraint, enabling seamless client-side Base64 encoding with complete file upload support—essential for embedding binary data in JSON APIs and debugging data URLs.