Storacha to FOC Migration: Support Scripts

Helper scripts that sit alongside the storacha space migrate workflow.

Scripts

• scripts/backup-helper/ — utilities for running the migration internally, from a FOC Node.
• scripts/prepare-cars-download/ — read a migration state.json and prepare a bulk CAR download manifest for aria2.
• scripts/migration-repair/ — convert shardsToStore entries (slow Store flow) into shards entries (fast Pull flow) by computing missing pieceCIDs locally, then patching the state file. Also lists skippedUploads and large roots for manual handling.

Requirements

Node.js 24+ for all scripts.