Fix CodeTailor Parsons blocks mangling comparison operators

[aspadiyath]

Before embedding the generated "---"-separated block markup into a

 element, coach.py ran

re.sub(r"<(?=\S)", "< ", block) to keep a bare "<" in the code from being misread as an HTML tag when parsons.js re-parses the element's innerHTML. That regex fired on every "<" followed by a non-space, so Python comparison operators were corrupted in the puzzle: "hours <= 1" rendered (and got dragged into the assembled solution) as "hours < = 1", and the code no longer ran.

Escape "<" to "<" instead. The Parsons widget already renders escaped entities back to their literal characters (that's how DB-authored markup survives extract_parsons_code), so the blocks now show "<=" correctly with no tag-injection risk. Only "<" is escaped, matching the original scope -- bare "&"/">" were never touched and render fine inside 
.

The clipboard "copy answer" path is unaffected: it uses the separate first ||split|| segment (the plain code solution), not the escaped block markup.