image_layout(
tss,width,class_attr,img_w,img_h,cell_w,cell_h) ->cols,pad_str,rows
Compute display layout for an inline PNG image
Resolves an image's display width in columns from its size class
(small/medium in class_attr, else the default w), reading values
from the image TSS object: fractions (<1) of the content width or
absolute columns. When the terminal cell pixel width is known, the
result is capped at the image's natural size so small images are never
upscaled. Returns the column count, the left padding string that
centers the image, and the estimated row count (true cell aspect ratio
when both cell dimensions are known, 2:1 otherwise).