Create Self-Contained .NET Deployment

[KSemenenko]

Configure project for self-contained single-file deployment without Docker.
Technical Details:
bashdotnet publish -c Release -r win-x64 --self-contained -p:PublishSingleFile=true
dotnet publish -c Release -r linux-x64 --self-contained -p:PublishSingleFile=true
dotnet publish -c Release -r osx-x64 --self-contained -p:PublishSingleFile=true
Definition of Done:

✅ Single executable for Windows/Linux/macOS
✅ Configuration via appsettings.json
✅ Auto-start scripts (Windows Service/systemd)
✅ Installation scripts for each platform
✅ No external dependencies required