Fix run duration filtering at any timescale

The duration histogram in the run filters bucketed every run shorter than ten seconds into a single column, so a fast test was drawn a full second away from its real duration and the slider could not select it.

• Fixed the histogram collapsing short runs into one column — it now spans the real range of the runs you are filtering, down to milliseconds
• Fixed the slider handles not lining up with the bars, and typed values like 0.4s being rounded away to no bound at all
• Fixed the histogram failing to load when the run list was filtered by sample, procedure version or environment