Storage Worker

While talking with @yangwao about our current architecture.
We found out that our pinning service slightly suck.

The proposed idea:
- export same interface as `nft-storage` has
- when user requests to pin a content
- pin it via `nft-storage` worker
- call to store the data `direct-upload`
- `direct-upload` needs to be extended with ability to store non-image content on r2 ^-^

Smol preview of architecture

Start by reviewing the repository's existing worker structure and the direct-upload entry point, then compare the requested interface with nft-storage. Trace how pin requests and R2 storage currently work. Done means a storage worker exposes the compatible interface, routes pinning through nft-storage, and supports non-image direct uploads to R2.

Written by the indexing model from the issue text.