Show Per-Device Differences Between Summary Dashboard Runs

Summary Dashboards currently display an overall trend indicator but do not show which specific devices or checks contributed to an improvement or degradation between runs. Users monitoring a continuously running or periodically scheduled dashboard have no way to identify what changed since the previous run without manual comparison. This enhancement would add a detail view or drill-down that highlights the specific devices and checks whose status changed between the current and prior run. Customers relying on frequently refreshed dashboards would gain faster insight into emerging issues and improvements, reducing the manual effort needed to interpret trend changes.