CrewSync PWA - Codebase Audit, PayPal Live Activation & Local Bank Payment Integration

I'm looking for an experienced full-stack developer to take CrewSync - a production-grade airline crew scheduling PWA - across the finish line to live deployment. The app is already built using Replit (vibe coded mostly). It's a React 18 / TypeScript PWA with a Node.js + Express backend, PostgreSQL (Drizzle ORM), Firebase Auth, Google Calendar OAuth, and a fully-wired PayPal subscription billing system (schema, routes, webhook processor, admin UI, paywall, entitlement middleware) that is currently dormant behind a kill switch. What I need you to do: 1. Full codebase & architecture audit - Review the entire stack and deliver a written report and documentation covering architecture, security posture, database integrity, and any gaps or risks before go-live. 2. PayPal live activation - Set up live credentials, sync subscription plans to PayPal's live catalog, verify webhook signature verification. 3. BML iPay integration — Integrate Bank of Maldives iPay as a second payment gateway for MVR (Maldivian Rufiyaa) payments. I will supply the merchant account, API credentials, and BML developer docs. The integration must mirror the existing PayPal flow: hosted redirect, payment confirmation callback, subscription activation via the same state machine. (BML does not support recurring subscriptions, each payment must be made manually by the user) 4. Freemium tier - Define free vs. paid features together with me, insert the plans into the DB, and confirm the entitlement middleware enforces the gate correctly. 5. Go-live deployment (app is already live with real users, only payment is disabled) Tech stack you must be comfortable with: Node.js / Express / TypeScript, React 18, PostgreSQL / Drizzle ORM, Firebase Admin SDK, PayPal REST API, REST payment gateway integration, PWA / service workers. Code quality standards are high - this is a real production app with real users.