Prepend velocity index 0 = max over all velocities (per scene, per pixel) to
showConvKernel5dHyperRect, and scale the display range to that slice instead
of the fixed IMP_MINMAX, so the small (~0.1) maxima are visible on open. It is
the first slice ImageJ shows - a quick map of non-empty pixels before scanning
scenes (Z) and velocities (T). Applies to both -HYPER-RECT and -DNN-HYPER-RECT.
Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>