Creates a CSS selector that targets SVG elements by their ID pattern, without relying on panel structure or hardcoded values.
generate_robust_css_selector(grob_name, svg_element)A robust CSS selector string, or NULL if grob_name is invalid
The name of the grob (e.g., "graphics-plot-1-rect-1")
The SVG element type to target (e.g., "rect", "polyline")