feat(rustproxy): add HTTP/3 proxy service wiring for QUIC listeners

rust/crates/rustproxy/src/lib.rs

@@ -845,6 +845,10 @@ impl RustProxy {
                             connection_registry,
                         );
                         udp_mgr.set_proxy_ips(conn_config.proxy_ips);
+                        // Wire up H3ProxyService so QUIC connections can serve HTTP/3
+                        let http_proxy = listener.http_proxy().clone();
+                        let h3_svc = rustproxy_http::h3_service::H3ProxyService::new(http_proxy);
+                        udp_mgr.set_h3_service(std::sync::Arc::new(h3_svc));
                         self.udp_listener_manager = Some(udp_mgr);
                     }
                 }