My friend just builts cloaked bots and runs through my base killing all my economy buildings and cloaking and walking away. I am used to having the ability to place "Detector" units down in other games, but a quick search online shows there is no such unit that can sweep an area in this game
You do that by walking your unit near to it or forcing it to fire. Since you don't initially know where exactly this "near" is, it is usually done by spawning and spreading a lot of cheap units in strategical chokepoints. Since the clocked units are usually weak in a hand-to-hand battle with a raider, such decloak usually ends up in the cloaked unit being destroyed.
Starve the opponent of energy source. Cloak usually consumes power, so denying that power automatically decloaks enough units to compensate.
Remember, that decloaking is temporary, and each cloaking unit will cloak again if left alone and the owner has enough power.