Replace the loop_face-only box padding with a single grid padding applied to
the first auto-center grid scan for any loop box (loop_all or loop_face). It
pads each side by a fraction of the grid size (daq.auto_raster.grid_padding_
fraction_x / _y, default 0.15), with a minimum of one cell per side, and
extends *before* cell 0 too so smargon_top_left shifts outward. Manual grid
(get_ml_bounding_box) is unchanged (grid_padding defaults off).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>