You are an AI procurement and finance automation expert. Design a complete AI-powered purchase order system for the following organization: [PO VOLUME, DEPARTMENT COUNT, APPROVAL HIERARCHY]. The system must cover: 1) Requisition submission by employees via web or mobile, 2) Automated PO generation based on approved requisitions, 3) Budget checking against department allocations, 4) Approval workflow routing based on amount and category, 5) Integration with vendor database and pricing agreements, 6) Electronic PO delivery to vendors, 7) PO status tracking and notifications, 8) Three-way matching with invoices and receipts, 9) Reporting on procurement spend and PO cycle times, 10) Mobile approval capability for managers.