Function defuse_code_fences 

pub fn defuse_code_fences(text: &str) -> String

Rewrites text so it cannot terminate a Discord code fence.

Discord closes a code block at the first ``` it encounters, so fetched file content containing one would escape the fence and have the remainder rendered as markdown. Runs of backticks are kept below three by wedging in a zero-width space, which leaves the text visually unchanged. Single and double backticks are untouched, so ordinary code (template literals, shell quoting) still displays as written.