Migrate React/Vite/Tailwind app from Base44 to Independent Supabase Backend

I have a fully designed kids' video streaming application called Flick Flow. The frontend layout, UI animations, and glassmorphism styling are built using React, Vite, and Tailwind CSS. The codebase is actively synced to a personal GitHub repository and deployed on Vercel. Right now, the application's backend architecture, data queries, and user authentication are hard-tethered to Base44's internal API wrappers (using hooks like base44.auth.me(), base44.entities.Video, and custom integration packages). I want to migrate away from Base44 completely to achieve zero-fee hosting and true platform independence. Your Scope of Work: Cleanly strip out all base44 ecosystem dependencies, packages, environment variables, and proprietary API wrappers from the codebase. Re-write the authentication context to utilize the official @supabase/supabase-js client SDK instead of base44.auth. Migrate and map all existing frontend views and forms (Sign-up, User Roles, Parental Passcode Math Gates, Video Upload feeds, and Public Profiles) to read and write directly to an external Supabase PostgreSQL database. Implement Apple's official child-safety and age-assurance frameworks for iOS compatibility. The developer must review Apple's latest Kids Category requirements and integrate Apple's native Declared Age Range API (or its current equivalent supported framework) into the application architecture. The system should utilize Apple-provided age-range and parental-consent signals whenever available, allowing Flick Flow to determine whether a child account has appropriate parental authorization through Apple's ecosystem rather than relying entirely on custom-built verification workflows. The implementation must be documented and designed to support future iOS and App Store compliance requirements. Set up safe client-side CRUD database operations. Note that Row Level Security (RLS) is already enabled on my Supabase tables—you will be responsible for creating the exact PostgreSQL RLS policies to authorize data transfers securely based on our custom user roles (kid, teen, adult, parent, admin). Ensure the final standalone repository builds flawlessly on Vercel using VITE_SUPABASE_URL and VITE_SUPABASE_ANON_KEY variables, resulting in a live, bug-free web application with all features working. All final code updates must be pushed back to my private GitHub repository. Please provide examples of past React + Supabase migration work when applying.