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/modules/__init__.py

@@ -10,6 +10,7 @@ from .childsetup import ChildSetup
 from .device import DeviceModule
 from .glassdetection import GlassDetection
 from .homekit import HomeKit
+from .lastalertdetection import LastAlertDetection
 from .led import Led
 from .lensmask import LensMask
 from .linecrossingdetection import LineCrossingDetection
@@ -33,6 +34,7 @@ __all__ = [
     "ChildSetup",
     "DeviceModule",
     "GlassDetection",
+    "LastAlertDetection",
     "Led",
     "LineCrossingDetection",
     "MeowDetection",