[router] Refactor OpenAI router: split monolithic file and move location (#11359)

sgl-router/src/routers/mod.rs

@@ -19,12 +19,13 @@ pub mod factory;
 pub mod grpc;
 pub mod header_utils;
 pub mod http;
+pub mod openai; // New refactored OpenAI router module
 pub mod router_manager;
 
 pub use factory::RouterFactory;
 
-// Re-export HTTP routers for convenience (keeps routers::openai_router path working)
-pub use http::{openai_router, pd_router, pd_types, router};
+// Re-export HTTP routers for convenience
+pub use http::{pd_router, pd_types, router};
 
 /// Core trait for all router implementations
 ///