Function strip_heredoc 

pub fn strip_heredoc(input: &str) -> String

Strip a whole-input heredoc wrapper; mirrors patch-parser.ts:33-36.

The TypeScript regex uses a backreference for the closing delimiter. Rust’s regex crate intentionally omits backreferences, so this uses regex for the opening heredoc syntax and then verifies the matching closing delimiter manually to preserve the same anchored wrapper behavior.