fix: handle nonconformed Notification in handshake

We skip Notification message in step. MCP doesn't allow the server to
send this. However, in real world, some popular servers do this anyway.
We should still try to handle this robustly by skipping such message.

Author: quangIO

crates/rmcp/src/service/client.rs

@@ -82,11 +82,21 @@ async fn expect_response<T>(
 where
     T: Transport<RoleClient>,
 {
-    let msg = expect_next_message(transport, context).await?;
-
-    match msg {
-        ServerJsonRpcMessage::Response(JsonRpcResponse { id, result, .. }) => Ok((result, id)),
-        _ => Err(ClientInitializeError::ExpectedInitResponse(Some(msg))),
+    loop {
+        let msg = expect_next_message(transport, context).await?;
+        match msg {
+            ServerJsonRpcMessage::Response(JsonRpcResponse { id, result, .. }) => {
+                break Ok((result, id));
+            }
+            ServerJsonRpcMessage::Notification(notification) => {
+                let notification = serde_json::to_string(&notification).unwrap_or_default();
+                tracing::debug!(
+                    notification,
+                    "Received notification from server when handshaking"
+                )
+            }
+            _ => break Err(ClientInitializeError::ExpectedInitResponse(Some(msg))),
+        }
     }
 }