guard macro expansion loops in the transpiled evaluator because
expand_macro→eval_expr→CEK can't handle let+first/rest in macro
bodies. Removed guard macro; will re-add as special form once
transpiler handles runtime AST construction (cons/append/make-symbol).
Fixed null? to handle empty lists (not just nil).
Fixed boolean=? to use = instead of undefined eq?.
2561/2568 tests pass (37 new vs baseline, 5 guard + 2 scope pending).
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
giles
3c419501e1