We are seeking an expert Full-Stack Developer to design and build a complex SaaS platform similar to PassKit. This platform will allow our clients (merchants) to create, manage, and distribute digital loyalty cards directly to their customers' Apple Wallet and Google Wallet. This is not a simple website project. It requires deep knowledge of mobile wallet APIs, cryptographic signing, and secure subscription billing. Core Project Requirements: Merchant Panel (SaaS Dashboard): Full user authentication system (Signup/Login). Dashboard for merchants to design their loyalty cards (upload logos, choose colors, define reward structure). Customer management section to view loyalty cardholders and their point balances. Stripe Subscription Integration: Integration of Stripe Billing (Subscriptions) for our SaaS revenue. Access to the Merchant Panel must be restricted based on an active Stripe subscription status. Implementation of webhooks to handle plan upgrades, downgrades, and cancellations securely. Mobile Wallet Integration (The Core): Apple Wallet: Must handle dynamic generation of signed .pkpass files. You must be familiar with generating and using Apple WWDR certificates for server-side signing. Google Wallet: Integration with the Google Wallet REST API to generate "Save to Google Wallet" links. Real-time Updates: When a merchant adds points to a customer's balance, the digital card inside the user's phone must update automatically via push notifications (Apple PNS and Google Wallet Webhooks). Customer Enrollment Flow: Generate a unique sign-up page or QR code for each merchant. A simple mobile-optimized form for the merchant's customers to enroll and immediately download their new loyalty card. Technical Stack Preference: Backend: PHP 8.x (with PDO) or Node.js. Database: MySQL. Frontend: Clean HTML/CSS/JavaScript (or a framework like React/Vue). Required Qualifications: Proven Experience with Apple PassKit (server-side pass generation) and Google Wallet API. Deep experience with Stripe API (specifically Subscriptions/Billing). Solid understanding of security best practices (SSL, data encryption, SQL injection prevention).