- new install-service.sh: creates/removes the OpenCode web UI systemd service as its own process (interactive by default, flags for automation, --uninstall, --dry-run, backs up an existing unit)
- install.sh no longer embeds the service logic; run_service_setup locates the sibling script (or downloads it) and invokes it as a separate process
- README documents running install-service.sh on its own
