Official portable binaries for macOS / Linux / Windows

### Requested feature

It would be very helpful if Docling provided official self-contained binaries for macOS, Linux, and Windows.

Right now, portable usage seems to require custom packaging and manual handling of runtime dependencies, resource folders, model artifacts, and native libraries. That makes deployment harder than it should be, especially for desktop apps, enterprise environments, offline setups, and users who do not want to manage a Python environment.