feat: 实现最小 BigInt 子集（字面量/算术/比较/构造器，Temporal 前置）

crates/oxide_vm/src/bindings/bind_bigint.rs

@@ -0,0 +1,33 @@
+use std::sync::Arc;
+
+use crate::bindings::{apply_binding_table, bind_global_value, configure_native_constructor};
+use oxide_kernel::kernel::{KernelCore, KernelSession};
+use oxide_types::object::JsObject;
+use oxide_types::value::JsValue;
+
+/// 把 BigInt 构造器与原型方法绑定到 global。
+///
+/// 构造器/原型对象由 `BuiltinWorld` 创建（含 name/prototype/constructor 互指），
+/// 这里只配置 native 实现并挂方法。`BigInt(value)` 当函数调用时返回 BigInt 值；
+/// `new BigInt()` 抛 TypeError（BigInt 不可 new）。
+pub fn bind_bigint(core: &Arc<KernelCore>, session: &KernelSession, global: &mut JsObject) {
+    let world = session.builtin_world();
+    let ctor_ptr = world.bigint_constructor.as_ptr() as *mut JsObject;
+    let ctor = unsafe { &mut *ctor_ptr };
+    let proto_ptr = world.bigint_proto.as_ptr() as *mut JsObject;
+    let proto = unsafe { &mut *proto_ptr };
+
+    configure_native_constructor(ctor, oxide_builtins::bigint::bigint_constructor::<crate::vm::Vm> as *const (), 1);
+
+    apply_binding_table(
+        world,
+        proto,
+        core,
+        &[
+            ("toString", oxide_builtins::bigint::bigint_to_string::<crate::vm::Vm> as *const (), 0),
+            ("valueOf", oxide_builtins::bigint::bigint_value_of::<crate::vm::Vm> as *const (), 0),
+        ],
+    );
+
+    bind_global_value(core, global, "BigInt", JsValue::from_js_object(ctor_ptr));
+}