Senior Full-Stack Developer for CRM MVP

About the Project: I am the founder of a new "Zero-Clutter" B2B CRM tailored for sales professionals. We are stepping away from bloated, slow legacy systems and focusing purely on deal-closing speed. The platform features a high-end, dark-mode aesthetic ("Midnight Hunter" design language) that feels like a premium cockpit rather than boring administration software. We already have a high-fidelity, clickable UI codebase generated via Lovable. Your job is to take this frontend foundation, refine it, and build a rock-solid backend infrastructure to bring the MVP to life. The Tech Stack: Frontend: React / Next.js / Tailwind CSS (Utilizing the existing Lovable UI codebase to save time) Backend & Database: Supabase (PostgreSQL, Auth, Storage) Hosting: Vercel (I will provide the accounts, infrastructure remains under my company's ownership) Core MVP Features to Build: Architecture & Security: Strict SaaS multi-tenancy. Company A must never be able to access Company B’s data. Smart CRM & Kanban: A smooth, drag-and-drop sales pipeline for managing deals. KVK API Integration: Integration with the Dutch Chamber of Commerce (KVK) API. When a user types a company name, the system must instantly autofill the address, registration number, and VAT details. Interactive Web-Quotes (The Core USP): Instead of static PDFs, the CRM must generate a secure, unique web-link for a quote. This web-quote must feature interactive "toggles" (e.g., the end-client can check a box for an upsell, and the total price recalculates live) and a basic E-signing module to close the deal online. Project Terms & Scope: Contract Type: Strictly Fixed-Price (No hourly billing). Budget is fully secured. Milestones: Payments will be divided into clear, logical milestones (e.g., 25% upfront, 25% backend/API ready, 50% upon successful bug-free deployment and IP transfer). Intellectual Property: Full IP and codebase ownership transfers to my company upon payment. NDA: You must be willing to sign a standard NDA before we share the Lovable codebase. Who I Am Looking For: You are a senior developer or a highly capable small team. You have proven, verifiable experience building SaaS platforms with React and Supabase. You communicate proactively. I do not micro-manage, but I expect clear, honest updates. You think along with the product. If you see a better way to structure the database, you speak up. How to Apply (READ CAREFULLY): To prove you are not a bot and have actually read this briefing, please start your proposal with the word "MIDNIGHT". Additionally, please answer this one technical question in your proposal:Question: We are building a multi-tenant B2B application on Supabase. How will you technically ensure that users from 'Tenant A' cannot read or mutate data belonging to 'Tenant B' at the database level? Please include 2-3 links to relevant SaaS projects you have built using this exact stack. I will select the top 3 candidates for a short video interview and a demo of the prototype this week.