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/thread-stream/test/ts/to-file.ts

@@ -0,0 +1,10 @@
+import { type PathLike, type WriteStream, createWriteStream } from 'fs'
+import { once } from 'events'
+
+export default async function run (
+  opts: { dest: PathLike },
+): Promise<WriteStream> {
+  const stream = createWriteStream(opts.dest)
+  await once(stream, 'open')
+  return stream
+}