GraphQL

Add --graphql to the three CLI commands to serve the models on /graphql (GraphiQL on GET /graphql) :

octopux --bootstrap --sqlite --graphql
octopux generate-model --name Author --fields --sqlx --migration --graphql --sqlite
octopux generate-model --name Book --fields --sqlx --migration --foreign-keys --graphql --sqlite
octopux generate-relation --parent Author --child Book --foreign-key=author_id --sqlx --migration --graphql --sqlite

Each model gets the author(id) and authors(offset, limit) queries and the createAuthor, updateAuthor and deleteAuthor mutations, merged into the schema of src/main.rs. Relations become fields:

query {
  authors(limit: 10) {
    id
    name
    books(limit: 5) { id title }
  }
}