fix: Redis authentication and etcd connection handling

Fixes two production issues:

1. NOAUTH Redis authentication error:
   - application.ex: Read password from application config
   - exq_supervisor.ex: Read password from application config
   - Both were bypassing runtime.exs config by reading env directly

2. EtcdCoordinator FunctionClauseError:
   - connect_etcd/0 now returns connection name (:towerops_etcd)
   - eetcd functions expect the atom name, not the PID
   - Fixes crash when trying to acquire locks

lib/towerops/monitoring/etcd_coordinator.ex

@@ -130,7 +130,15 @@ defmodule Towerops.Monitoring.EtcdCoordinator do
       ~c"etcd-2.etcd.towerops.svc.cluster.local:2379"
     ]
 
-    :eetcd.open(:towerops_etcd, endpoints)
+    case :eetcd.open(:towerops_etcd, endpoints) do
+      {:ok, _pid} ->
+        # Return the connection name (atom), not the PID
+        # eetcd functions expect the connection name
+        {:ok, :towerops_etcd}
+
+      {:error, _reason} = error ->
+        error
+    end
   end
 
   defp handle_watch_event(%{type: :delete, kv: %{key: key}}, conn) do