fix: capture 404 requests in middleware

[Jah-yee]

Description

Remove the early return when context.GetEndpoint() is null, so that 404 Not Found requests are captured by the middleware instead of being skipped.

Changes

Removed the following block from DebugProbeMiddleware.cs (8 lines):

var endpoint = context.GetEndpoint();

if (endpoint is null)
{
    await _next(context);
    return;
}

Why

• Debugging missing routes is a common scenario
• Developers often need visibility into invalid requests
• Monitoring unexpected traffic is useful
• APIs frequently receive malformed or outdated routes

Fixes #53

[georgidhristov]

Thanks for the contribution.