feat: 注入 harness 并补齐关键全局内建

crates/oxide_vm/tests/builtins_array_tests.rs

@@ -187,6 +187,15 @@ fn array_empty_literal() {
     assert_eq!(obj.prop_count(), 0);
 }
 
+#[test]
+fn array_is_array_static_method() {
+    let (_vm, result) = eval("Array.isArray([])").unwrap();
+    assert_eq!(result, JsValue::bool(true));
+
+    let (_vm, result) = eval("Array.isArray({})").unwrap();
+    assert_eq!(result, JsValue::bool(false));
+}
+
 #[test]
 fn array_shift_removes_first() {
     let (_vm, result) = eval("[1,2,3].shift()").unwrap();