[router] move tokenizer, reasoning, tool initialization to server (#9996)

sgl-router/tests/test_pd_routing.rs

@@ -195,7 +195,8 @@ mod test_pd_routing {
 
             // Router creation will fail due to health checks, but config should be valid
             let app_context =
-                sglang_router_rs::server::AppContext::new(config, reqwest::Client::new(), 64, None);
+                sglang_router_rs::server::AppContext::new(config, reqwest::Client::new(), 64, None)
+                    .expect("Failed to create AppContext");
             let app_context = std::sync::Arc::new(app_context);
             let result = RouterFactory::create_router(&app_context).await;
             assert!(result.is_err());