Use most recent available data when historical path calculation window has no benchmark

When running a historical path calculation for a specific point in time, the calculation currently fails if no benchmark data exists within the configured time window around that point, requiring users to widen the window manually. This enhancement would allow the path calculation to use the most recent available data at or before the selected time, rather than requiring data to fall strictly within a fixed window. Customers would benefit from historical path calculations that remain reliable even when device data collection has gaps, reducing failed calculations and manual window adjustments.