As of April 2025 Spotify no longer allows insecure redirect URIs which complicates initial Spotify setup.
* Improve spotify App creation instructions
* Add several approaches to creating a valid redirect URI
* Remove Spotify as the default Source example in docs due to complexity of Redirect URI requirements
Closes#330
* Allows users to define a base URL to be used for default redirect URI generation
* Convenience mostly for docker users so they do not have to explicitly define redirect uri for each source/client
* Use in UI start up logging hints
