I have an existing electronic-invoicing website that I need duplicated, front-end and back-end, within 48 hours. The core requirement is that the invoicing system—including its automated invoice generation flow—works exactly as it does now; no extra fields, templates, or design tweaks are necessary... (Budget: $30 - $250 USD, Jobs: API Development, Database Management, Frontend Development, HTML, JavaScript, PHP, Web Application, Web Design, Web Development, Website Design)