Bare metal installations couldn't serve Windows host agent downloads because
the Windows and macOS binaries weren't included in the universal tarball. The
download endpoint would return 404 when Windows users tried to install the
host agent from a bare metal Pulse deployment (Proxmox LXC, Debian VM, etc.).
Changes:
- build-release.sh: Copy Windows/macOS host agent binaries into universal tarball
- build-release.sh: Create symlinks for Windows binaries without .exe extension
- validate-release.sh: Add Windows 386 binary and symlink to Docker validation
- validate-release.sh: Add explicit validation that universal tarball contains all Windows/macOS binaries
The universal tarball now matches the Docker image, ensuring both deployment
methods can serve the complete set of downloadable binaries for the /download/
endpoint.