fix: register PeerCenterRpc in management API server so CLI peer-center works (#1929)

PeerCenterRpc was only registered in the per-instance peer-to-peer RPC
manager (domain = network_name), but not in the management API server
(domain = ""). The CLI connects to the management API with an empty
domain, causing "Invalid service name: PeerCenterRpc" errors.

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

easytier/src/connector/udp_hole_punch/sym_to_cone.rs

@@ -616,7 +616,7 @@ pub mod tests {
                     .await
                     .is_ok()
             },
-            Duration::from_secs(10),
+            Duration::from_secs(30),
         )
         .await;
         println!("{:?}", p_a.list_routes().await);