js-on-sx: scope var defines + js-args for call args

JS top-level var was emitting (define <name> X) at SX top level,
permanently rebinding any SX primitive of that name (e.g. var list
= X broke (list ...) globally). Two-part fix:
1. wrap transpiled program in (let () ...) in js-eval so defines
   scope to the eval and don't leak.
2. rename call-args constructor in js-transpile-args from list to
   js-args (a variadic alias) so even within the eval's own scope,
   JS vars named list don't shadow arg construction.
Array-literal transpile keeps list (arrays must be mutable).
built-ins/Object: 41/50 → 42/50. conformance.sh: 148/148.

plans/js-on-sx.md

@@ -158,6 +158,8 @@ Each item: implement → tests → update progress. Mark `[x]` when tests green.
 
 Append-only record of completed iterations. Loop writes one line per iteration: date, what was done, test count delta.
 
+- 2026-05-07 — **JS top-level `var` no longer pollutes SX global env; call args use `js-args` to avoid `list` shadow.** `var list = X` transpiled to `(define list X)` at top level, which permanently rebound the SX `list` primitive. Then any later code (including the runtime itself) calling `(list ...)` got "Not callable: <X>". Two-part fix: (1) wrap the whole transpiled program in `(let () ...)` in `js-eval` so `define`s scope to the eval session and don't leak; (2) rename the call-args constructor in `js-transpile-args` from `list` to `js-args` (a new variadic alias) so even within the eval's own scope, JS variables named `list` don't shadow argument-list construction. Array-literal transpile keeps `list` (lists must be mutable). built-ins/Object: 41/50 → 42/50; Array.from on array-likes now works. conformance.sh: 148/148.
+
 - 2026-05-07 — **`Object.__callable__` returns `this` for `new Object()` no-args path.** `js-new-call Object` had `obj.__proto__ = Object.prototype` already set, but then Object.__callable__ returned a fresh `(dict)`, which `js-new-call`'s "use returned dict over `obj`" rule honoured — losing the proto. Added a `is-new` check (`this.__proto__ === Object.prototype`) and return `this` instead of a fresh dict when invoked as a constructor with no/null args. Now `new Object().__proto__ === Object.prototype`, `Object.prototype.isPrototypeOf(new Object())`, and `.constructor === Object` all work. built-ins/Object: 37/50 → 41/50. conformance.sh: 148/148.
 
 - 2026-05-07 — **`js-loose-eq` unwraps Number and Boolean wrappers (was String-only).** `Object(1.1) == 1.1` was returning `false`: loose-eq only had a clause for `__js_string_value__`. Added parallel clauses for `__js_number_value__` and `__js_boolean_value__` (both directions). Now `new Number(5) == 5`, `Object(true) == true`, etc. built-ins/Object: 26/50 → 37/50. conformance.sh: 148/148.