use timestamp as device class for sensors reporting time

hass-workstation-service/Domain/Sensors/LastActiveSensor.cs

@@ -18,7 +18,8 @@ namespace hass_workstation_service.Domain.Sensors
                 Device = this.Publisher.DeviceConfigModel,
                 State_topic = $"homeassistant/{this.Domain}/{Publisher.DeviceConfigModel.Name}/{this.Name}/state",
                 Icon = "mdi:clock-time-three-outline",
-                Availability_topic = $"homeassistant/{this.Domain}/{Publisher.DeviceConfigModel.Name}/availability"
+                Availability_topic = $"homeassistant/{this.Domain}/{Publisher.DeviceConfigModel.Name}/availability",
+                Device_class = "timestamp"
             });
         }
 

hass-workstation-service/Domain/Sensors/LastBootSensor.cs

@@ -22,7 +22,8 @@ namespace hass_workstation_service.Domain.Sensors
                 Device = this.Publisher.DeviceConfigModel,
                 State_topic = $"homeassistant/{this.Domain}/{Publisher.DeviceConfigModel.Name}/{this.Name}/state",
                 Icon = "mdi:clock-time-three-outline",
-                Availability_topic = $"homeassistant/{this.Domain}/{Publisher.DeviceConfigModel.Name}/availability"
+                Availability_topic = $"homeassistant/{this.Domain}/{Publisher.DeviceConfigModel.Name}/availability",
+                Device_class = "timestamp"
             });
         }