Terminal-rendering helpers for Severity used by jsdet’s CLI
output. Lives here because secfinding stays presentation-agnostic
(no ANSI color codes), and adding methods directly to the foreign
enum is forbidden by Rust’s orphan rules. Importing this trait
(use jsdet_core::analysis::SeverityVisuals;) brings .icon()
and .color_code() back into scope wherever the old inherent
methods were called.