fix: replace deprecated huggingface-cli with hf command

fix: wait for server readiness before WAL checkpoint, use 127.0.0.1 not localhost

fix: WAL checkpoint before backup — DB was 4KB (schema only) because WAL held all data

debug: add verbose logging to entrypoint.sh backup — remove 2>/dev/null, use portable wc -c

fix: persist DB via HF Dataset repo — bucket FUSE mount doesn't support SQLite writes

fix: persist SQLite via backup/restore — bucket FUSE mount doesn't support SQLite locking