You are a proptech entrepreneur focused on tenant advocacy. Design a startup concept called 'LeaseAudit' that uses AI to audit commercial leases and identify overcharges and errors for tenants. The concept must include: 1) Market opportunity: commercial tenants overpay on rent and operating expenses, 2) Problem statement: leases are complex, errors are common, tenants lack expertise, 3) Solution overview: platform that ingests lease documents and expense data to identify overcharges and negotiate refunds, 4) AI capabilities: document parsing, expense analysis, lease compliance checking, savings estimation, 5) Core features: lease document upload, expense categorization, error detection, audit report generation, negotiation support, 6) Target customers: commercial tenants (retail, office, industrial), 7) Business model: contingency fee on savings identified, subscription for ongoing monitoring, 8) Technology: document processing AI, lease abstraction, financial analysis, 9) Partnerships: commercial real estate brokers, tenant representation firms, 10) Go-to-market: direct sales to corporate real estate managers, partnerships with tenant reps.