chore: checkpoint before Python removal

vendor/wasip3/examples/cli-command.rs

@@ -0,0 +1,19 @@
+wasip3::cli::command::export!(Example);
+
+struct Example;
+
+impl wasip3::exports::cli::run::Guest for Example {
+    async fn run() -> Result<(), ()> {
+        let (mut tx, rx) = wasip3::wit_stream::new();
+
+        futures::join!(
+            async { wasip3::cli::stdout::write_via_stream(rx).await.unwrap() },
+            async {
+                let remaining = tx.write_all(b"Hello, WASI!".to_vec()).await;
+                assert!(remaining.is_empty());
+                drop(tx);
+            }
+        );
+        Ok(())
+    }
+}