Feature request: Proper types in shape log

**Is your feature request related to a problem? Please describe.**
Why does the shape API serialize every column as a string? It makes it difficult/inefficient to decode JSON to model types on the client for example in Swift. I either have to write a custom decoder to parse every string to its proper type on the client which is inefficient, or modify server code to recast every type properly. Both of these solutions are difficult to maintain and introduce inefficiency either on the server or the client, which makes me wonder why electric doesn't just do this directly?

**Describe the solution you'd like**
Encode columns best effort to their respective JSON type.