Updated Visual Studio version in the solution file to 17.14.36717.8.
Added three new projects: Infrastructure, Domain, and Application,
all targeting .NET 8.0. Enabled implicit global usings and nullable
reference types in the new projects. Updated solution configuration
and nested the new projects under the `src` folder.
Added a `Worker` class as a hosted background service to log
periodic messages. Updated `DigitalData.EmailProfiler.API.csproj`
to include `UserSecretsId` for secure development storage and
added `Microsoft.Extensions.Hosting` package. Replaced the
`Controllers` folder reference with `Properties`. Updated
`Program.cs` to register the `Worker` service, enable API
exploration, and retain Swagger configuration.
