My web application was prototyped in Google AI Studio and is already live in a sandbox environment, but a handful of thorny issues are blocking the ability to launch the app live. I’d like an experienced web-app engineer to comb through the code, confirm it meets best practices, and then resolve filtering errors based on the monetization model. Additionally, I need to connect a payment gateway and validate that it works. I will grant access and share environment credentials as soon as we start. A concise change log, commented commits, and a short validation report explaining what you reviewed and why you adjusted it will be the acceptance criteria.