Revoke a user API key

Revoke an API key for a user. Revocation is terminal: a revoked key can no longer authenticate any request, and the revocation cannot be undone. Only the authenticated user themselves and server admins have access to this endpoint. When authenticated with a user API key, only that key itself may be revoked: a key can always destroy itself, but it cannot revoke the user's other keys. Authenticate with a JWT (user session token) to revoke other keys.