chore: 调整项目演示程序目录结构

examples/migpt/src/runtime.rs

@@ -0,0 +1,18 @@
+use std::future::Future;
+
+use once_cell::sync::OnceCell;
+use tokio::runtime::Runtime;
+
+static RUNTIME: OnceCell<Runtime> = OnceCell::new();
+
+pub fn runtime() -> &'static Runtime {
+    RUNTIME.get_or_try_init(Runtime::new).unwrap()
+}
+
+pub fn run_async<F>(future: F)
+where
+    F: Future + Send + 'static,
+    F::Output: Send + 'static,
+{
+    runtime().spawn(future);
+}