perf(nodes): Connected Nodes refresh — parallel probes, instant list, 12s health timeout

Reachability probes ran one at a time with a 30s Tor timeout each, so
Refresh sat disabled for N-offline-peers × 30s. Now the list renders and
the button re-enables immediately; probes run concurrently and fill the
dots in as they land.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

core/archipelago/src/node_message.rs

@@ -406,7 +406,10 @@ pub async fn check_peer_reachable(onion: &str, fips_npub: Option<&str>) -> Resul
     validate_onion(onion)?;
     match crate::fips::dial::PeerRequest::new(fips_npub, onion, "/health")
         .service(crate::settings::transport::PeerService::Messaging)
-        .timeout(std::time::Duration::from_secs(30))
+        // 12s, not 30s: this is a liveness dot, not a data transfer. A Tor
+        // circuit that hasn't answered /health in 12s is "offline" for UI
+        // purposes; the old 30s made the Connected Nodes probes crawl.
+        .timeout(std::time::Duration::from_secs(12))
         .send_get()
         .await
     {