Stable publishing for native software

This is a bucket to contain the work required to make stable the support for publishing C++ and other native software to binary repositories.

Some candidate features:

- User documentation, including samples, dsl guide, tutorials, etc.
- Publish and resolve C++ and other native libraries via a repository.
- Publish and resolve C++ and other native executables via a repository.
- Publish and resolve static libraries, header-only libraries, resource-only libraries.
- Support for Maven and Ivy repositories.
- Support for conan.io and NuGet repositories.
- Stable enough `maven-publish` and `ivy-publish` plugins. For example, this might mean that the configuration DSL and APIs are stable, but the extensibility APIs are not.
- Upload tasks run in parallel by default.

The issue does not identify files, tests, or entry points. Start by narrowing the candidate work areas—documentation, repository publishing and resolution, Maven/Ivy, conan.io, NuGet, publishing plugins, and parallel uploads—and define which subset is in scope; done would require stable support for the selected area.

Written by the indexing model from the issue text.