Refactor last_fm configuration

Move all configuration outside of the LastFm module, so that it's not
polluted with references to the parent music_library application.

config/config.exs

@@ -24,6 +24,13 @@ config :music_library, MusicLibraryWeb.Endpoint,
   pubsub_server: MusicLibrary.PubSub,
   live_view: [signing_salt: "g/qw4SNo"]
 
+config :music_library, LastFm,
+  # to avoid runtime errors, set the user to a valid Last.fm username
+  user: "username",
+  api: LastFm.APIImpl,
+  refresh_interval: System.convert_time_unit(60, :second, :millisecond),
+  api_key: "change me"
+
 # Configure esbuild (the version is required)
 config :esbuild,
   version: "0.17.11",

config/dev.exs

@@ -62,6 +62,9 @@ config :music_library, MusicLibraryWeb.Endpoint,
 # Enable dev routes for dashboard and mailbox
 config :music_library, dev_routes: true
 
+config :music_library, LastFm,
+  refresh_interval: System.convert_time_unit(500, :second, :millisecond)
+
 # Do not include metadata nor timestamps in development logs
 config :logger, :console, format: "[$level] $message\n"
 

config/runtime.exs

@@ -24,6 +24,10 @@ if api_key = System.get_env("LAST_FM_API_KEY") do
   config :music_library, LastFm, api_key: api_key
 end
 
+if user = System.get_env("LAST_FM_USER") do
+  config :music_library, LastFm, user: user
+end
+
 if config_env() == :prod do
   database_path =
     System.get_env("DATABASE_PATH") ||

config/test.exs

@@ -28,4 +28,4 @@ config :phoenix, :plug_init_mode, :runtime
 config :phoenix_live_view,
   enable_expensive_runtime_checks: true
 
-config :music_library, :last_fm, nil
+config :music_library, LastFm, api: nil