Scaffolds bd preflight for PR readiness checks. Currently prints a static checklist of common pre-PR validation items: - Tests pass - Lint passes - No beads pollution - Nix hash current - Version sync --check and --fix flags are documented but not yet implemented (see bd-lfak.2 through bd-lfak.5 for roadmap). (bd-lfak.1) Cherry-picked from polecat/amber-1767146829144 🤖 Generated with [Claude Code](https://claude.com/claude-code) Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>