[router][grpc] Fix streaming bugs: empty tool names, state pollution, and panics (#11373)

sgl-router/tests/common/mod.rs

@@ -4,6 +4,7 @@
 pub mod mock_mcp_server;
 pub mod mock_openai_server;
 pub mod mock_worker;
+pub mod streaming_helpers;
 pub mod test_app;
 
 use serde_json::json;