Create Discord app

We need to set up a prod instance of the `discord-server-info` Discord application in the [Discord Developer Portal](https://discord.com/developers/applications).

This app will allow us to:

- connect our bot to and interact with Discord
- authenticate our Next.js app users with Discord

We'll also need to add instructions for contributors to create their own Discord application so they can run the bot locally for development.

We don't need this in order to do development work so this can likely be one of the final steps before we launch the MVP.

Start in the Discord Developer Portal and review how the Next.js app and bot currently expect Discord credentials and authentication to be configured. Done means a production application exists for the bot and user authentication, and contributor instructions explain how to create a local Discord application for development.

Written by the indexing model from the issue text.