feat: 提取 oxide_builtins 独立 crate，泛型化 <H: VmHost>

crates/oxide_builtins/src/stubs.rs

@@ -0,0 +1,31 @@
+use oxide_runtime_api::{NativeResult, VmHost};
+
+fn stub_error<H: VmHost>(vm: &mut H, name: &str) -> NativeResult {
+    NativeResult::Err(crate::error::create_type_error(vm, &format!("{name} is not implemented")))
+}
+
+// Architecturally deferred — these features are excluded from the supported language subset by design.
+pub fn proxy_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "Proxy")
+}
+pub fn bigint_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "BigInt")
+}
+pub fn weakmap_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "WeakMap")
+}
+pub fn weakset_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "WeakSet")
+}
+pub fn weakref_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "WeakRef")
+}
+pub fn finalization_registry_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "FinalizationRegistry")
+}
+pub fn shared_array_buffer_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "SharedArrayBuffer")
+}
+pub fn atomics_stub<H: VmHost>(vm: &mut H, _args: &[u8]) -> NativeResult {
+    stub_error(vm, "Atomics")
+}