Expense Report Builder

Build an expense report tool with PostgreSQL:
1. Create expense report with title, date range, purpose
2. Add expense items: date, category, merchant, amount, description
3. Category dropdown (Travel, Meals, Supplies, Software, Other)
4. Expense report summary with category totals
5. Submit for approval workflow
6. Report history with status (Draft, Submitted, Approved, Reimbursed)

Database: expense_reports (id, title, employee_name, date_from, date_to, purpose, status, total), expenses (id, report_id, date, category, merchant, amount, description). Seed with 5 reports and 30 expenses.