Restore same-URL guard in replaceServer

Accidentally dropped during the Music tab removal edit; without it,
reapplying the current URL recreates the session and loses history.

Sources/Features/Conversation/ConversationView.swift

@@ -72,6 +72,7 @@ struct ConversationView: View {
             // Coalesce rapid Apply actions; construct from the captured URL.
             while let next = pendingServerURL {
                 pendingServerURL = nil
+                guard next != activeServerURL else { continue }
                 await session.disconnect()
                 activeServerURL = next
                 session = Self.makeSession(next, settings: settings)