kernel: multi-expression body for $vau/$lambda + 5 tests [nothing]

:body slot holds a LIST of forms now (was single expression). New
knl-eval-body in eval.sx evaluates each form in sequence, returning
the last. $vau and $lambda accept (formals env-param body...) /
(formals body...). No $sequence dependency. 223 tests total.

lib/kernel/eval.sx

@@ -172,9 +172,19 @@
             (when
               (not (= eparam :knl-ignore))
               (kernel-env-bind! local eparam dyn-env)))
-          (kernel-eval (get op :body) local)))
+          ;; :body is a list of forms — evaluate in sequence, return last.
+          (knl-eval-body (get op :body) local)))
       (:else (error "kernel-call-operative: malformed operative")))))
 
+(define knl-eval-body
+  (fn (forms env)
+    (cond
+      ((= (length forms) 1) (kernel-eval (first forms) env))
+      (:else
+        (begin
+          (kernel-eval (first forms) env)
+          (knl-eval-body (rest forms) env))))))
+
 ;; Phase 3 supports a flat parameter list only — destructuring later.
 (define
   kernel-bind-params!