Redesign Reports page with 4 tabs: Overview, Purchases, Sales, Compare

- Overview: Business volume, quick stats, payment breakdown, trend chart, top items
- Purchases: Detailed purchase analysis with filters, item breakdown, payment summary
- Sales: Detailed sales analysis with filters, item breakdown, payment summary
- Compare: Side-by-side purchase vs sales comparison with charts and item bars
- Modern UI with hero cards, stats grids, and card-based layout
- Date filtering: All, Year, Month, Week, Today, Custom
- CSV and PDF export functionality

Author: hiteshkrmsft