Fix alerts page by migrating old equipment_* alert types to device_*

The Alert schema was updated to use :device_down and :device_up enum values,
but existing database records still had 'equipment_down' and 'equipment_up' values.

Added migration to update all existing alert records to use the new naming
convention.

priv/repo/migrations/20260117231451_update_alert_types_equipment_to_device.exs

@@ -0,0 +1,15 @@
+defmodule Towerops.Repo.Migrations.UpdateAlertTypesEquipmentToDevice do
+  use Ecto.Migration
+
+  def up do
+    # Update existing alert records from old "equipment_*" naming to "device_*" naming
+    execute("UPDATE alerts SET alert_type = 'device_down' WHERE alert_type = 'equipment_down'")
+    execute("UPDATE alerts SET alert_type = 'device_up' WHERE alert_type = 'equipment_up'")
+  end
+
+  def down do
+    # Revert back to old naming if needed
+    execute("UPDATE alerts SET alert_type = 'equipment_down' WHERE alert_type = 'device_down'")
+    execute("UPDATE alerts SET alert_type = 'equipment_up' WHERE alert_type = 'device_up'")
+  end
+end