- Add `include_trends` query parameter to enable trend calculation
- Implement trend comparison logic (delta % and direction) against previous periods
- Add support for `last7d`, `last30d`, and `all` time period options
- Update `DashboardSummaryResponse` to include optional `trends` field
- Add helper functions for custom time window aggregation
- Add unit tests for trend calculation and period window logic
- Update feature documentation with new parameters and response schemas