"touch latch" or "push latch"
also in this style:
keep in mind this doesn't need to be mounted right next to the edge, since you only have 1/8" lip. you could mount it behind the tablet body even just a little ways down from the top... as long as it's up high enough that when it pushes out it comes far enough to get a finger behind the tablet and pull it free from the magnet. if you can't achieve that, then use the second non-magnetic style - but note that once pushed then the tray/door would flop open all the way instead of only coming out a bit.