C# IDisposable, IAsyncDisposable and using statements: why and when

// ======================================================================
// Q: IDisposable and using: why and when?
//
// For unmanaged or expensive resources (connections, file handles, streams) that
// must be released immediately, not whenever the GC runs. using calls Dispose
// even on an exception. IAsyncDisposable / await using for async cleanup.
// Whatever the DI container creates, the container disposes at the end of the
// scope. Do not Dispose injected services. Finalizers only if you directly hold
// an unmanaged handle (rare; usually SafeHandle).
// ======================================================================

await using var stream = File.OpenRead(path);   // Dispose at the end of the scope
using var activity = ActivitySource.StartActivity("ImportPrices");