Multi-Tenant SaaS Platform: Accounting, POS, Inventory & HR (React/Node)

We're building MRM Portal, a multi-tenant SaaS platform for SMBs in the UAE/GCC region that unifies financial operations, retail POS, workforce management, and customer engagement in one role-based system. Full platform scope (for context — we're not expecting all of this delivered quickly): Multi-tenant Super Admin panel, subscription billing, seat management Sales & Invoicing (invoices, recurring invoices, estimates, PDF/QR generation) Purchases (vendor bills, expense tracking with AI/OCR receipt scanning, approvals) Inventory & Procurement (multi-warehouse, batch tracking, purchase orders) POS (web, Android & iOS, barcode scanning, offline mode, cash-drawer integration) Banking & reconciliation CRM (customers, vendors, leads pipeline) Accounting (chart of accounts, journal entries, ledger, trial balance, P&L) HR & Payroll (employee profiles, attendance, leave, payroll, salary slips) Calendar & Booking (staff scheduling, appointments) Reports (Excel/Word/PDF export & import, UAE VAT/Corporate Tax reporting) Social media integration (Facebook, Instagram, LinkedIn, X) Role-based access, AI assistant (OCR + auto expense creation) Flutter mobile companion app (iOS & Android) How we want to work: This is an ongoing engagement, not a rushed fixed-price sprint. We're building this in phases rather than expecting full delivery all at once, and we'll prioritize modules together as we go (likely starting with core invoicing/accounting/CRM before POS, HR, and the mobile app). Open to discussing whether hourly or milestone-based pricing makes more sense once we've talked through scope and pace. Preferred stack: React + TypeScript frontend, Node.js/Express or Laravel backend, PostgreSQL, Flutter for mobile. Open to alternatives if you can justify the trade-offs. In your proposal, please include: Your experience with multi-tenant SaaS/ERP builds (links or examples) Milestone-based How you'd sequence the modules above Your typical availability/response time for async collaboration