isSafeHeredoc function
Check if a heredoc is safe (delimiter is quoted/escaped).
Implementation
bool isSafeHeredoc(String command) {
final heredocMatch = RegExp(r'<<-?\s*(\S+)').firstMatch(command);
if (heredocMatch == null) return true;
final delimiter = heredocMatch.group(1)!;
// Quoted delimiter is safe
if (delimiter.startsWith("'") || delimiter.startsWith('"')) return true;
// Escaped delimiter is safe
if (delimiter.startsWith(r'\')) return true;
// Unquoted delimiter allows variable substitution — potentially unsafe
return false;
}