Updates build script and release checklist to include pulse-temp-proxy binaries:
- Build pulse-temp-proxy for all architectures (amd64, arm64, armv7)
- Include in tarballs alongside pulse and pulse-docker-agent
- Copy standalone binaries to release/ for install-temp-proxy.sh
- Update release checklist to upload standalone binaries as assets
This ensures install-temp-proxy.sh can download binaries from GitHub releases.