c991e3f62f
scripts/desktop-update/posix.sh is the mac/linux twin of windows.ps1: the Desktop spawns it detached and QUITS; it waits the app out, runs plain hermes update (retry-once across the update boundary, truthful desktop-rebuild completion), swaps/relaunches the .app bundle (mac) or the release/*-unpacked binary when its sandbox helper is launchable (linux), writes .hermes-update-result.json, and drives the same shim. Repo-owned, so every update refreshes the code that drives the next one. resolvePosixScriptHandoff mirrors the Windows resolver (with the flat-path fallback covering the scripts/ reorg skew).