fix(rustproxy-http): reuse the shared HTTP proxy service for HTTP/3 request handling

rust/crates/rustproxy-passthrough/src/tcp_listener.rs

@@ -428,6 +428,11 @@ impl TcpListenerManager {
         self.http_proxy.prune_stale_routes(active_route_ids);
     }
 
+    /// Get a reference to the HTTP proxy service (shared with H3).
+    pub fn http_proxy(&self) -> &Arc<HttpProxyService> {
+        &self.http_proxy
+    }
+
     /// Get a reference to the connection tracker.
     pub fn conn_tracker(&self) -> &Arc<ConnectionTracker> {
         &self.conn_tracker