Fix Dialyzer pattern match coverage warning

- Replace catch-all pattern with explicit :unknown status handling
- Makes status transitions more explicit and type-safe
- Resolves pattern_match_cov warning at line 174

lib/towerops/monitoring/equipment_monitor.ex

@@ -171,7 +171,8 @@ defmodule Towerops.Monitoring.EquipmentMonitor do
           {:alert_resolved, equipment_id, :equipment_down}
         )
 
-      _ ->
+      {_, :unknown} ->
+        # Status is unknown - no action needed
         :ok
     end
   end