fix reset_zoom button

[hubuke]

Fix waveform end time and reset zoom behavior

Problem

The waveform end time was previously determined by the timestamp of the last STOPMESSAGE.
In the dashboard, a STOPMESSAGE is only sent when the user clicks Re-fetch Data, unless
core_analyzer is run after the experiment. This caused the waveform time range to include
idle time between the end of the experiment and when the data was fetched.

Solution

• Use the timestamp of the last non-STOPMESSAGE as the waveform end time
• Add 10% padding after the end time to visually indicate the endpoint

Result

• Reset Zoom now correctly zooms to the full waveform range
• Eliminates extra idle-time padding in the waveform view

Related terms

• auto zoom
• zoom all

This PR relate/depends on #2922

[hubuke]

need to add support for uniform_interval