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/reusify/reusify.d.ts

@@ -0,0 +1,14 @@
+interface Node {
+	next: Node | null;
+}
+
+interface Constructor<T> {
+	new(): T;
+}
+
+declare function reusify<T extends Node>(constructor: Constructor<T>): {
+	get(): T;
+	release(node: T): void;
+};
+
+export = reusify;