fix: prevent CLOSED messages from terminating relay connections

The system was incorrectly treating subscription-specific CLOSED messages
as connection-wide disconnects, causing live subscriptions to be terminated
immediately after historic_sync completed.

Two bugs fixed:
1. relay_connection.rs: Removed break on RelayMessage::Closed - it's
   subscription-specific, not connection-wide
2. mod.rs: Removed disconnect handling for RelayEvent::Closed - only log
   at DEBUG level and continue

All 41 sync tests now pass including previously failing live sync tests.

1 files changed, 2 insertions, 1 deletions

diff --git a/src/sync/relay_connection.rs b/src/sync/relay_connection.rs
index bc4b59e..fdb32cb 100644
--- a/src/sync/relay_connection.rs
+++ b/src/sync/relay_connection.rs
@@ -256,7 +256,8 @@ impl RelayConnection {
                                 tracing::info!(relay = %url, message = %msg, "Relay closed subscription");
                                 let _ =
                                     event_sender.send(RelayEvent::Closed(msg.to_string())).await;
-                                break;
+                                // Don't break - CLOSED is subscription-specific, not connection-specific
+                                // The event loop should continue running for other active subscriptions
                             }
                             _ => {}
                         },