[router] fix grpc connection conversion and add optimization (#11305)

sgl-router/src/grpc_client/sglang_scheduler.rs

 use std::convert::TryFrom;
 use std::time::Duration;
 use tonic::{transport::Channel, Request};
-use tracing::{debug, warn};
+use tracing::debug;
 
 use crate::protocols::spec::{
     ChatCompletionRequest, GenerateRequest, ResponseFormat,
@@ -27,28 +27,23 @@ impl SglangSchedulerClient {
     pub async fn connect(endpoint: &str) -> Result<Self, Box<dyn std::error::Error + Send + Sync>> {
         debug!("Connecting to SGLang scheduler at {}", endpoint);
 
-        // Convert grpc:// to http:// for tonic, preserving IPv6 bracket notation
-        let http_endpoint = if endpoint.starts_with("grpc://") {
-            // Use proper URL parsing to preserve IPv6 brackets
-            match url::Url::parse(endpoint) {
-                Ok(mut parsed) => {
-                    let _ = parsed.set_scheme("http");
-                    parsed.to_string()
-                }
-                Err(_) => {
-                    warn!(
-                        "Failed to parse gRPC endpoint '{}', using simple string replacement",
-                        endpoint
-                    );
-                    endpoint.replace("grpc://", "http://")
-                }
-            }
+        // Convert grpc:// to http:// for tonic
+        let http_endpoint = if let Some(addr) = endpoint.strip_prefix("grpc://") {
+            format!("http://{}", addr)
         } else {
             endpoint.to_string()
         };
 
         let channel = Channel::from_shared(http_endpoint)?
             .timeout(Duration::from_secs(30))
+            .http2_keep_alive_interval(Duration::from_secs(30))
+            .keep_alive_timeout(Duration::from_secs(10))
+            .keep_alive_while_idle(true)
+            .tcp_keepalive(Some(Duration::from_secs(60)))
+            .tcp_nodelay(true)
+            .http2_adaptive_window(true)
+            .initial_stream_window_size(Some(16 * 1024 * 1024)) // 16MB
+            .initial_connection_window_size(Some(32 * 1024 * 1024)) // 32MB
             .connect()
             .await?;