Adds build support for 32-bit Windows (windows-386) for pulse-host-agent.
Changes:
- Add windows-386 build to Dockerfile host-agent build section
- Add windows-386 binary copy and symlink to Dockerfile
- Add windows-386 build to build-release.sh
- Add windows-386 zip package to release artifacts
- Include windows-386 binary in standalone binary copies
This enables pulse-host-agent to run on 32-bit Windows systems, which are still relevant in legacy/industrial monitoring environments through late 2025.