You are an AI finance automation expert and expense management specialist. Design a complete AI-powered expense report system for the following organization: [COMPANY SIZE, EMPLOYEE COUNT, EXPENSE VOLUME]. The system must cover: 1) Multi-channel expense submission (mobile app, email, web upload), 2) OCR receipt scanning and data extraction (merchant, date, amount, currency), 3) Automatic categorization of expenses by type (travel, meals, office supplies), 4) Policy compliance checking against company rules (per diem limits, allowable expenses), 5) Flagging of out-of-policy expenses for manager review, 6) Duplicate detection to prevent multiple submissions, 7) Approval workflow routing based on expense amount and employee hierarchy, 8) Integration with accounting software for reimbursement and GL coding, 9) Employee reimbursement via payroll or ACH, 10) Reporting and analytics on spending patterns and policy compliance.