Add PinePhone ARM64 SD image target with Codex CLI

Add ARM64 Docker image target

Add Docker image build target with env-based bootstrap

Add fresh-machine install helper script and installer docs

Add ISO build verification details and ignore build artifacts

Add first-boot guidance command and enable it in installer/host

Add flake lock and remove legacy module

Switch to official nix-openclaw flake + web-only first-boot setup

Scaffold flake-based OpenClaw NixOS + installer ISO project