runtime: complete Object.create descriptor and prototype validation semantics #2816

Summary

Object.create currently only models Object.create(proto). Node also supports Object.create(proto, propertiesObject) and requires the prototype argument to be either an object or null; primitives and undefined throw TypeError.

Perry's current runtime/lowering ignores the descriptor argument and treats non-object prototypes like null/prototype-less objects, which hides invalid input and drops own properties from descriptor-form clones.

Expected Node behavior

Local Node v25.9.0 probe:

Object.getPrototypeOf(Object.create(null)) === null; // true

const p = { x: 1 };
const o = Object.create(p);
console.log(Object.getPrototypeOf(o) === p, o.x, Object.keys(o)); // true, 1, []

Object.create(1);         // TypeError: Object prototype may only be an Object or null
Object.create("x");       // TypeError
Object.create(undefined); // TypeError

const d = Object.create(
  { p: 1 },
  {
    a: { value: 2, enumerable: true },
    b: { value: 3, enumerable: false },
  },
);
console.log(d.p, d.a, d.b, Object.keys(d)); // 1, 2, 3, ["a"]
console.log(Object.getOwnPropertyDescriptor(d, "b").enumerable); // false

Current Perry implementation

Source evidence from current tree:

• crates/perry-hir/src/lower/expr_call/object_static.rs lowers "create" to Expr::ObjectCreate(Box::new(iter.next().unwrap_or(Expr::Undefined))), discarding every argument after the first.
• crates/perry-hir/src/lower/expr_call/native_module.rs does the same for direct Object.create(...) calls.
• crates/perry-hir/src/ir/expr.rs only has ObjectCreate(Box<Expr>), so there is no HIR slot for the optional descriptor object.
• crates/perry-codegen/src/expr/array_methods.rs lowers Expr::ObjectCreate to one runtime call: js_object_create(proto).
• crates/perry-codegen/src/runtime_decls/strings.rs declares js_object_create with one DOUBLE argument.
• crates/perry-runtime/src/object/object_ops.rs::js_object_create() comments that Object.create(null) or a non-object proto falls back to a prototype-less object. Node only permits null; non-object, non-null prototypes must throw.
• docs/typescript-parity-gaps.md already notes Object.create() is limited and lacks the property descriptors argument, but there is no open issue tracking the concrete runtime/API work.

Suggested test surface

Add parity tests for:

const proto = { p: 1 };
const obj = Object.create(proto, {
  a: { value: 2, enumerable: true },
  b: { value: 3, enumerable: false },
});
assert.equal(obj.p, 1);
assert.equal(obj.a, 2);
assert.equal(obj.b, 3);
assert.deepEqual(Object.keys(obj), ["a"]);
assert.equal(Object.getOwnPropertyDescriptor(obj, "b")!.enumerable, false);

assert.throws(() => Object.create(1 as any), TypeError);
assert.throws(() => Object.create(undefined as any), TypeError);
assert.equal(Object.getPrototypeOf(Object.create(null)), null);

Scope / non-goals

This is not about the already-fixed Object.create(proto) prototype-chain wiring or instanceof behavior (#1805 / PR #2244, #809 / PR #815). It tracks the remaining descriptor-form Object.create(proto, propertiesObject) behavior and prototype-argument validation.