v1.4.2: Requirement stats now pick best session per requirement

Requirement breakdown previously used the single best Domain 3 session
for all 12 requirements. A focused Requirement 11 quiz at 100% was
invisible if a larger Domain 3 quiz had more total correct answers.

Each requirement is now evaluated independently: the session where the
user answered the most questions correctly for that specific requirement
wins, so focused requirement drills are properly reflected.

Co-Authored-By: Craft Agent agents-noreply@craft.do