Function smart_resize 

pub fn smart_resize(
    h: u32,
    w: u32,
    factor: u32,
    min_pixels: u64,
    max_pixels: u64,
) -> (u32, u32)

2026-09-25: Snap each side to the nearest multiple of factor, then rescale by the area bounds if the snapped canvas violates them.

factor = patch_size * merge_size, and the bounds are areas in pixels. Returns (h_bar, w_bar), both multiples of factor and at least one factor each. The initial snap rounds (so a 360-pixel side at factor 28 becomes 364, and the canvas may be larger than the input), the over-budget branch floors, and the under-budget branch ceils.