Function apply_scale_to_svg 

pub(crate) fn apply_scale_to_svg(svg: &str, scale: f32) -> String

Apply a direct scale to the provided SVG markup by inserting a <g transform="scale(...)"> around the SVG contents and multiplying simple numeric width/height attributes when present. It also adjusts a viewBox attribute’s width/height so that SVGs that rely on viewBox sizing are not cropped after applying the transform.

This is intentionally lightweight (string-based) to avoid pulling in an XML parser as a dependency. It handles common cases emitted by Mermaid and similar tools, but leaves complex or non-numeric attributes unchanged.