Create monorepo using pnpm

[benjreinhart]

README.md has instructions

Essentially we now have:

├── pnpm-workspace.yaml
├── packages/
│   ├── api/
│   ├── shared/
│   └── web/
└── package.json

I moved the zod schemas and types into the shared package, as well as one util function.

[benjreinhart]

I did not add CI or more tests in this PR, we can do that as a follow up.

[nichochar]

Awesome, thanks for this. Particularly excited about the shared stuff

[nichochar]

Is this valid json !?