fix(viewer): close the endpoint on all post-connect failure paths

open_bi/bind/local_addr/accept all `?`-propagated straight out of run(),
skipping the endpoint.close().await at the end and leaking the iroh
Endpoint on any post-connect error. Wrap the post-connect body in one
block whose result is captured, then close unconditionally — matching
the explicit-close idiom of the connect-phase select arms.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/viewer/mod.rs

@@ -50,6 +50,11 @@ pub async fn run(ticket: EndpointTicket, opts: ViewerOpts) -> Result<()> {
             }
         },
     };
+    // Everything past the established connection runs in one block so any error
+    // (open_bi, bind, local_addr, accept) is captured rather than `?`-propagated
+    // straight out of the function — that would skip the close below and leak the
+    // endpoint. The connect-phase arms above close explicitly for the same reason.
+    let result = async {
         let (quic_send, quic_recv) = conn.open_bi().await?;
 
         let listener = TcpListener::bind(("127.0.0.1", opts.port)).await?;
@@ -67,7 +72,7 @@ pub async fn run(ticket: EndpointTicket, opts: ViewerOpts) -> Result<()> {
             print_viewer_banner(&url);
         }
 
-    let result = tokio::select! {
+        tokio::select! {
             accepted = listener.accept() => {
                 let (tcp, peer) = accepted?;
                 tracing::info!(%peer, "local viewer connected");
@@ -77,7 +82,9 @@ pub async fn run(ticket: EndpointTicket, opts: ViewerOpts) -> Result<()> {
                 tracing::info!("ctrl-c received before local viewer connected");
                 Ok(())
             }
-    };
+        }
+    }
+    .await;
 
     endpoint.close().await;
     result