Merge pull request #90 from smeinecke/feat/add-account-proxy

Thanks @smeinecke for the rebase — duplicate config / setup / docs from #88 are cleaned up nicely. Merging.

I noticed the proxy validation ordering inside `addAccount` (account is still created before `body.proxy` is parsed/validated) wasn't moved in this revision — I'll fix that in a follow-up commit on master right after this merges, since you've already done the heavy lifting on the feature itself. No further action needed from you. Will also add the `test/account-add-proxy.test.js` suite there.

Appreciated 🙏