feat: Include postgres enums in output

[schpet]

threw aider (llm coding tool) at trying to get a working implementation for this:

https://github.com/drwl/annotaterb/issues/176

i need to actually look at the code it wrote and revise this, but throwing it up so i can try it out. appears to generate desired output in my project.

todo:

• [ ] review code, make sure it all makes sense
• [ ] add tests