refactor: standardize project names to Musify.* and flatten layout

- Flatten nested per-repo folders into flat Musify.* projects at root
- Rename assemblies/csproj: Domain->Musify.Domain, Application->Musify.Application,
  Infrastructure->Musify.Infrastructure, WebApi->Musify.Api, Worker->Musify.Worker,
  StreamingGateway->Musify.StreamingGateway
- Rename WebApi.* namespaces to Musify.Api.*
- Update all ProjectReference paths and the solution file
- Consolidate stray per-repo dotfiles; add root .gitattributes
- Move flutter client out to _archive

Musify.Worker/Program.cs

@@ -0,0 +1,27 @@
+using Musify.Application.Configuration;
+using Musify.Infrastructure.MassTransit;
+using Musify.Infrastructure.Persistence;
+using Musify.Infrastructure.Services;
+using Musify.Worker;
+
+var builder = Host.CreateApplicationBuilder();
+
+var configuration = builder.Configuration;
+
+var services = builder.Services;
+
+services.AddApplicationStorageConfiguration(configuration);
+services.AddPlayListConfiguration(configuration);
+services.AddTrackConfiguration(configuration);
+services.AddStorageService(configuration);
+services.AddAudioTranscoder(configuration);
+services.AddPictureService(configuration);
+services.AddDatabase(configuration);
+services.AddMassTransitConsumers(configuration);
+services.AddUploadIntentJobs(configuration);
+
+services.AddHostedService<Worker>();
+
+var host = builder.Build();
+
+host.Run();