[Bug]: 'AmazonKidsSensor' object has no attribute 'alexa_entity_id'

### Describe the bug

Every 10 minutes the following ERROR log appears:

```
2026-09-12 14:39:11.272 ERROR (MainThread) [custom_components.alexa_media.coordinator] Unexpected error fetching alexa_media data
Traceback (most recent call last):
File "/srv/homeassistant/lib/python3.14/site-packages/homeassistant/helpers/update_coordinator.py", line 441, in _async_refresh
self.data = await self._async_update_data()
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/srv/homeassistant/lib/python3.14/site-packages/homeassistant/helpers/update_coordinator.py", line 315, in _async_update_data
return await self.update_method()
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/homeassistant/.homeassistant/custom_components/alexa_media/__init__.py", line 977, in async_update_data
entities_to_monitor.add(binary_sensor.alexa_entity_id)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
AttributeError: 'AmazonKidsSensor' object has no attribute 'alexa_entity_id'
```

### To Reproduce

ERROR log just appears without any specific action

### Expected behavior

Log shall not be showing up

### Screenshots

_No response_

### Home Assistant Version

2026.9.2

### Alexa Media Player Version

5.16.0

### Alexa Media Player API library Version

1.30.0

### Have you entered a 52-character key for Amazon 2SV via Authenticator App login?

No

### Is the HA core integration Alexa Devices installed?

No

### Amazon Domain

amazon.de (Germany)

### Amazon Domain (if Other)

_No response_

### Debug Logs (alexa_media & alexapy)

```text

```

### Additional context

_No response_