Function flint_decode 

pub fn flint_decode(s: &str) -> String

Decode the Ignition Flint JSON-string form back to plain text — SINGLE-PASS (multi-pass cannot distinguish \\t — literal backslash + t — from \t — a tab). Unknown \uXXXX and unknown single escapes KEEP the backslash (the ignition-nvim semantics: the escape sequence rides through verbatim for the re-encode).