Fixed ref() to map upstream JS variable names to let-bound SX variables
using element context (tag→var, id→var, make-return→last-var). Fixes
if (0→14/19), put (14→18), on (20→23), and other categories where the
upstream test uses make() return variables like d1, div, btn.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>