Custom Logistics Web App Development -- 2

I need a developer to convert my existing logistics web app from a no-code platform (Base44) into a fully custom system with backend owned by me.

The app is already partially built and includes:
- Shipment management (multi-modal: sea, land, air)
- Client portal (track shipments, invoices)
- Financials (invoices, costs, payments)
- Commission system (based on profit)
- Basic CRM (clients/contacts)

Scope of work:
- Rebuild backend using Supabase (preferred) or Node.js + PostgreSQL
- Connect existing frontend (React) or rebuild cleanly if needed
- Implement proper database structure
- Fix and optimize logic (payments, commissions, profit calculations)
- Ensure mobile responsiveness
- Remove dependency on Base44 completely

Requirements:
- Clean, scalable code
- Full source code ownership
- Experience with React + Supabase (or similar stack)
- Experience with ERP / logistics systems is a plus

Goal:
A stable, production-ready internal system for freight forwarding operations.

Budget:
Looking for cost-efficient solution (open to proposals), but quality and long-term stability are important.

Timeline:
Flexible, but prefer fast execution.

Please share:
- Similar projects (if any)
- Suggested tech stack
- Estimated cost and timeline