- Add file-hash.ts: SHA-256 hash of uploaded files via Web Crypto API
- Add datum-cache.ts: localStorage save/load/clear for datums by hash
- Add settings-cache.ts: persist scalePxPerMm and includeScaleBar
- Restore datums from cache on re-upload of same file
- Discreet "Clear cache" button on upload page
- Store fileHash and cacheRestoreMessage in Pinia store
- Auto-save datums on every change via deep watcher
- Track maxStepReached for clickable step navigation
Co-Authored-By: Claude <noreply@anthropic.com>
