[Workflow] Schema and LSP support for generate.toml

[amoeba]

I noticed in #43 that we're building out functionality in generate.toml and I think our users could use some help. We generate a very basic generate.toml on first run and then the user is kind of on their own. Docs would be a good follow-up.

tombi supports JSON schema for TOML (LOL) and I prototyped that at amoeba@2349bf7. With that commit, you get nice editor hovers for the fields:

@lidavidm suggested looking into pydantic or some tool to generate a JSON schema so I think I'll start there since I made my JSON schema by hand above.