- Install recharts for data visualization
- Add Usage nav item to sidebar navigation
- Create telemetry API service with data fetching functions
- Build dashboard page with summary cards, charts, and time range selector
- Token usage line chart, cost breakdown bar chart, task outcome pie chart
- Loading and empty states handled
- Responsive layout with PDA-friendly design
- Add unit tests (14 tests passing)
Refs #375
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>