One instance of INSTANCES.
name: string
Names its database and uploads, and prefixes its output. Lowercase letters, digits and hyphens.
apiPort: number
The port of its API server, GERBEUR_PORT.
webPort: number
The port of its Vite server, where its pages are.
optional
env: Record<string, string>
GERBEUR_* settings of its own, over the base .env: a site name, an
emoji or a style, to tell the instances apart, or which ways federated
sign-in goes.