AFAIK camera-ui(2) is available only for CSSU-Testing (or thumb), while you're using CSSU-Stable. You have to either switch to -Testing for this particular feature (and quite a bunch of other ones) - which is preferred way - or install camera-ui from CSSU-Testing separately - including all it's possible dependencies - creating some kind of hybid CSSU-Stable/Testing variant on your device.

I wouldn't recommend the latter, if you're not familiar with how repository system works in GNU/Linux -related operating systems. Not to mention that if you are familiar with it, there is no reason to use CSSU-Stable at first place...

/Estel