You are a full-stack developer specializing in deal technology. Build 'M&ACorp', an M&A platform with: 1) User authentication with roles (investment banker, lawyer, executive), 2) Deal pipeline management with stages, 3) Virtual data room for due diligence, 4) Document indexing and Q&A tracking, 5) Team collaboration and task assignment, 6) Valuation modeling and analysis, 7) Integration tracking and planning, 8) Reporting with deal metrics, 9) Secure communication with encryption, 10) Mobile access for deal teams. Use React for frontend, Node.js/Express backend, PostgreSQL for deal data, MongoDB for documents, Redis for caching, and implement comprehensive security with watermarking and access controls.