My food-delivery platform is in full production, but the stack is showing its age. The backend still runs on PHP 7.3 with a custom MVC mix of HTML/CSS/MySQL, while three Android apps (User, DeliveryBoy, Restaurant) compile against an older SDK. I now need a thorough code review and a clean migration path that brings everything up to date without breaking current users. Backend scope • Audit the existing PHP 7.3 codebase, flag outdated or deprecated patterns, then refactor or rewrite it in the latest stable Laravel release. • Ensure every controller, model, and query is compatible with PHP 8.x, maintaining current business logic and database schema. • Keep an eye on security practices, performance tuning, and future maintainability while you modernise the code. Android scope • Re-compile all three apps against the latest Android SDK so they remain compatible from older devices right through to Android 14. • Replace legacy notification code with the current Firebase Cloud Messaging approach; push alerts must land reliably on every model we support. • Check for and resolve any breaking changes linked to permissions, background services, or system-level battery optimisations. Deliverables 1. Git commits or pull requests showing the Laravel migration, documented line-by-line where logic changes occur. 2. Updated Gradle projects for User, DeliveryBoy and Restaurant apps, building cleanly on Android Studio stable channel. 3. End-to-end test results proving login, order flow and notifications across at least one old (API 21-23) and one new (API 34) device. 4. Deployment guide so my in-house team can reproduce the build and roll out updates with zero downtime. I’m looking to move fast, so let me know your estimated timeline for each milestone and any similar upgrade work you’ve done before.