Redirect ipfs.io/api/v0/*

[lidel]

I suspect some apps may leverage the fact that a subset of APIs is exposed under ipfs.io/api/v0/.

Companion should redirect things like https://ipfs.io/api/v0/cat?arg=/ipns/docs.ipfs.io/assets/logo.svg (especially ones with ranges and offsets) to maximize the use of local nodes.

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• Q: could this be a partial replacement for window.ipfs?
  • A: Yes, for basic read-only commands like ipfs.cat. People could simply code against https://ipfs.io/api/v0 and browsers with native support (or companion extension) would just redirect those requests to local node.