fix: simplify stale descriptor cleanup and fix ordering

Clean port descriptor before project descriptor so the global resource
is freed first. Pass gateway_port() directly since cleanup_port_descriptor
already handles None.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: lwshang

crates/icp-cli/src/commands/network/start.rs

@@ -91,10 +91,9 @@ pub(crate) async fn exec(ctx: &Context, args: &StartArgs) -> Result<(), anyhow::
                  Cleaning up and starting fresh.",
                 network.name
             );
+            nd.cleanup_port_descriptor(descriptor.gateway_port())
+                .await?;
             nd.cleanup_project_network_descriptor().await?;
-            if let Some(port) = descriptor.gateway_port() {
-                nd.cleanup_port_descriptor(Some(port)).await?;
-            }
         }
     }