fix backup status display, sync loop spin, and PM2 log leakage

feat(sync): skip backup when no state changes detected

reduce startup log verbosity

fix: adjust OAuth callback paths, force /app root redirect, and increase logging verbosity for sync processes

refactor: implement two-pass backup creation to automatically exclude frontend cache if tarball exceeds size limits

fix: move next build to container startup — HF builder cgroup too small

initialize project