refactor: keep aether timeline on cluster-aware nostr wrappers

Retain TimelineLive on the plugin-facing Nostr service after the host implementation switched to multi-relay defaults, so the plugin benefits from cluster-aware reads and publish fanout without falling back to direct host internals.

lib/aether_web/live/timeline_live.ex

@@ -95,7 +95,7 @@ defmodule AetherWeb.TimelineLive do
 
   @impl true
   def terminate(_reason, socket) do
-    if is_reference(socket.assigns[:subscription_ref]) do
+    if socket.assigns[:subscription_ref] do
       Nostr.unsubscribe(socket.assigns.subscription_ref)
     end