Disable authentication by default on Umbrel

[mononaut]

Umbrel v0.5 introduced authentication middleware for all apps by default, which redirects users to a login page before they can access Bitfeed.

Since Bitfeed does not expose any sensitive information, or access to user funds, authentication is probably unnecessary and only adds friction to the user experience.

Solution: add PROXY_AUTH_ADD: "false" to the umbrel docker-compose configuration.