Fix multi-line run scripts breaking shell syntax
The newline-to-semicolon substitution (${INPUT_RUN//$'\n'/;}) breaks
shell compound statements: blank lines produce ;;, and keywords like
then/do/else followed by ; are syntax errors in sh.
Pass the script directly to sh -c which handles newlines natively.
Co-authored-by: Cursor <cursoragent@cursor.com>