VoiceOS integrations are Mac-only only because of supportedPlatforms

VoiceOS Integration Studio scaffolds every integration for both platforms: the generated AGENTS.md says run.sh / run.cmd are 'the launchers VoiceOS invokes (macOS / Windows)', and both files are in each folder. What actually blocks Windows is the manifest's supportedPlatforms; with only ["darwin"], Windows users see 'App only supported for Mac.' The field isn't documented in the VoiceOS manifest reference, and integrations built on Macs often end up darwin-only. Before adding "win32", grep for macOS-only calls such as execFile('/usr/bin/open', [url]) for OAuth sign-in (it breaks on Windows; use voiceos:openUrl or pick the command by platform). A cheap CI guard: jq -e '.supportedPlatforms | index("win32")' voiceos.integration.json, with an exception when the README states 'macOS only'.