Whitespace standardization

See _harp/_data.json ; everyone's editor settings keep clashing and the JSON is kinda nasty-looking now.

.editorconfig files might be in order. Or, a git hook that lints. Do some research and come back.

huge fan of soft tabs, 2 spaces because that's "what real webdevs use" 🙃 but I don't feel like relitigating that fight.

Start by inspecting _harp/_data.json and the repository's existing configuration. Research the tradeoffs between adding .editorconfig files and using a git hook, then document a concrete recommendation and the whitespace standard that would be considered complete.

Written by the indexing model from the issue text.