Missing `white` Key in Backlight Data Structure

[leoherzog]

While running the server, I'm getting periodic errors when the backlight was set to an RGB value via the API:

Exception in callback <bound method ServerDialHandler.periodic_dial_update of <server_dial_handler.ServerDialHandler object at 0x7fa6af6cc0>>
Traceback (most recent call last):
  File "/opt/vu-server/venv/lib/python3.12/site-packages/tornado/ioloop.py", line 945, in _run
    val = self.callback()
          ^^^^^^^^^^^^^^^
  File "/opt/vu-server/server_dial_handler.py", line 46, in periodic_dial_update
    ret = self._periodic_update_dial_backlight()
          ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
  File "/opt/vu-server/server_dial_handler.py", line 133, in _periodic_update_dial_backlight
    dial['backlight']['white']
    ~~~~~~~~~~~~~~~~~^^^^^^^^^
KeyError: 'white'

The API wants RGB, but the internal data structure wants RGBW?