js-on-sx: js-iterable-to-list respects length on array-like dicts

Array.from({length: 3, 0: 'a', 1: 'b', 2: 'c'}) used to return ['3','a','b','c']
because js-iterable-to-list walked dict keys in insertion order and included
the 'length' key as a value.

Now the dict branch checks for 'length' key first — if present, delegates to
js-arraylike-to-list which reads indices 0..length-1. Otherwise falls back
to value-order for plain objects.

Fixes Array.from, spread (...dict), and destructure from array-likes.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

lib/js/runtime.sx

@@ -2195,10 +2195,14 @@
       ((list? v) v)
       ((= (type-of v) "string") (js-string-to-list v 0 (list)))
       ((dict? v)
-        (let
+        (cond
-          ((result (list)))
+          ((contains? (keys v) "length") (js-arraylike-to-list v))
-          (for-each (fn (k) (append! result (get v k))) (keys v))
+          (else
-          result))
+            (let
+              ((result (list)))
+              (begin
+                (for-each (fn (k) (append! result (get v k))) (keys v))
+                result)))))
       (else (list)))))
 
 (define