- Move box ID validation, file listing/pathing, manifest creation, and uploads to `boxstore`
- Use shared helpers for safe filenames and polling interval env parsing
- Add file status constants to `models` to avoid duplicated magic strings across handlersrefactor(server): use boxstore helpers and file status consts
- Move box ID validation, file listing/pathing, manifest creation, and uploads to `boxstore`
- Use shared helpers for safe filenames and polling interval env parsing
- Add file status constants to `models` to avoid duplicated magic strings across handlers
