dev-api: add developer portal, OpenAPI spec, and Flatenbadet case study

- New /developers/ page with API docs, SDKs, pricing, use cases
- OpenAPI 3.0 spec for Orders, Missions, Photos, Analytics
- Case study: Glasskiosken i Flatenbadet — complete ROI analysis
- Updated /order/ with recurring missions and frequency dropdown

services/frilans-payout/node_modules/postcss/lib/stringify.js

@@ -0,0 +1,11 @@
+'use strict'
+
+let Stringifier = require('./stringifier')
+
+function stringify(node, builder) {
+  let str = new Stringifier(builder)
+  str.stringify(node)
+}
+
+module.exports = stringify
+stringify.default = stringify