So it sounds like one of the advantages of the Zed ecosystem is that its data can go into three file formats (zson, zng, zst), each designed for a specific use case, and convert between them easily and without loss.

And it seems like the newer "zed lake" format is like a large blob managed by a server. Can you also convert data to and from and the file formats to the lake format? What is the lake's main use case?