Add LastAlertDetection module for smartcam devices (#1762)

Add a `LastAlertDetection` module for SMARTCAM devices exposing `getLastAlarmInfo` as two `Info` sensor features:

- `last_alert_timestamp` — tz-aware `datetime` of the last alert, `None` when the device has never detected anything (`last_alarm_time` is `""` or `"0"` on such devices, and an unexpected value is also mapped to `None`
- `last_alert_type` — `LastAlertType` enum (`Motion`; `Unknown` fallback with a one-time warning per unknown raw value), `None` when unset.

kasa/smartcam/smartcammodule.py

@@ -54,6 +54,10 @@ class SmartCamModule(SmartModule):
 
     SmartCamBattery: Final[ModuleName[modules.Battery]] = ModuleName("Battery")
 
+    SmartCamLastAlertDetection: Final[ModuleName[modules.LastAlertDetection]] = (
+        ModuleName("LastAlertDetection")
+    )
+
     SmartCamDeviceModule: Final[ModuleName[modules.DeviceModule]] = ModuleName(
         "devicemodule"
     )