Enable Admin Spotify Login Flow

[adambechtold]

When you first set up the app, you store one instance of a spotify access token to perform admin operations, like linking last.fm listens to the

We broke this admin flow when we set up in-memory session storage for end-users to play music from the web player 🤦

• Enable clear admin login flow
• Document admin login flow in the README

⚖️ Consideration - The seed data does not include an access token

Currently, the link the to admin flow is supposed to be at the /debug endpoint, which requires an Admin key

• ❓ Question - Is this the right place for it? Should it be more accessible?