Named let's sf-named-let used call-lambda which returns a thunk that
was never trampolined. The body executed in a disconnected env, so
set! couldn't reach outer let bindings. Fixed by using cek-call which
evaluates through the full CEK machine with proper env chain.
Also converted test-named-let-set.sx from assert= (uses broken = for
lists) to deftest/assert-equal (uses deep equal?).
JS standard: 1120/1120, JS full: 1600/1600. Zero failures.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>