Recommend native macOS and Windows builds in the README

## Problem
The README does not present the native macOS and Windows builds as the preferred installation and launch method. Once those builds are stable, users should be directed to them instead of developer-oriented setup paths.

## Proposed change
After the macOS and Windows builds are considered stable, update README.md so downloading and running the appropriate native build is the recommended installation method. Keep source-based setup instructions available for contributors and users who need them, but make their secondary role clear.

## Acceptance Criteria
- [ ] README.md recommends the stable native macOS and Windows builds as the primary installation method.
- [ ] The instructions link users to the correct download location.
- [ ] The documented steps explain how to install and launch each supported native build.
- [ ] Source-based installation remains documented but is clearly presented as an alternative or development workflow.
- [ ] The documentation change is made only after both native build workflows are stable.