fix: handle alert_changed messages in AgentLive.Index

The StatusTitleComponent (rendered in authenticated layout) subscribes
to organization:*:alerts PubSub topic. Since LiveComponents run in the
parent process, both the component and parent LiveView receive these
messages.

Added catch-all handler to prevent FunctionClauseError when alert
changes broadcast. The component already handles the message properly.

lib/towerops_web/live/agent_live/index.ex

@@ -398,6 +398,12 @@ defmodule ToweropsWeb.AgentLive.Index do
     {:noreply, maybe_update_agent(socket, agent_token_id, organization_id)}
   end
 
+  # Handled by StatusTitleComponent in layout - ignore to prevent crashes
+  @impl true
+  def handle_info({:alert_changed, _org_id}, socket) do
+    {:noreply, socket}
+  end
+
   @impl true
   def handle_info({:agents_stale, _stale_agents}, socket) do
     {:noreply, reload_agent_data(socket)}