Remove comments from backend and web-player source

Strip //, /* */ and XML doc comments from all backend .cs files, and
JS/TS/CSS/HTML comments from web-player source (.ts, .svelte, .css),
per the project's no-comments convention.

backend/Hosts/Musify.Api/Program.cs

@@ -48,6 +48,4 @@ app
 
 app.Run();
 
-// Makes the top-level-statements Program class public so
-// WebApplicationFactory<Program> (Musify.Api.Tests) can see it.
 public partial class Program;