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

@@ -50,34 +50,41 @@ pub async fn run(ticket: EndpointTicket, opts: ViewerOpts) -> Result<()> {
             }
         },
     };
-    let (quic_send, quic_recv) = conn.open_bi().await?;
+    // 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?;
-    let port = listener.local_addr()?.port();
-    let url = format!("http://127.0.0.1:{port}");
-    output::emit(output::Event::Connected { url: &url });
+        let listener = TcpListener::bind(("127.0.0.1", opts.port)).await?;
+        let port = listener.local_addr()?.port();
+        let url = format!("http://127.0.0.1:{port}");
+        output::emit(output::Event::Connected { url: &url });
 
-    if opts.interactive {
-        let player = crate::interactive::prompt_player()?;
-        player
-            .spawn(&url)
-            .with_context(|| "failed to launch player")?;
-        print_viewer_banner_interactive();
-    } else {
-        print_viewer_banner(&url);
+        if opts.interactive {
+            let player = crate::interactive::prompt_player()?;
+            player
+                .spawn(&url)
+                .with_context(|| "failed to launch player")?;
+            print_viewer_banner_interactive();
+        } else {
+            print_viewer_banner(&url);
+        }
+
+        tokio::select! {
+            accepted = listener.accept() => {
+                let (tcp, peer) = accepted?;
+                tracing::info!(%peer, "local viewer connected");
+                crate::common::tunnel::bridge(quic_send, quic_recv, tcp).await
+            }
+            _ = cancel.cancelled() => {
+                tracing::info!("ctrl-c received before local viewer connected");
+                Ok(())
+            }
+        }
     }
-
-    let result = tokio::select! {
-        accepted = listener.accept() => {
-            let (tcp, peer) = accepted?;
-            tracing::info!(%peer, "local viewer connected");
-            crate::common::tunnel::bridge(quic_send, quic_recv, tcp).await
-        }
-        _ = cancel.cancelled() => {
-            tracing::info!("ctrl-c received before local viewer connected");
-            Ok(())
-        }
-    };
+    .await;
 
     endpoint.close().await;
     result