Function padding_row 

pub fn padding_row(commit_line: &str, style: GraphStyle) -> String

Build a “breather” row that mirrors the current lanes but only shows vertical glyphs — useful for expanded styles (BubblesX) which insert one or more padding rows between commits to leave breathing room.

Pass the commit_line of the commit we’re padding under; this function derives lane positions from it (any non-space char becomes a lane glyph of style.lane_glyph()).