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/math-intrinsics/isInteger.js

@@ -0,0 +1,16 @@
+'use strict';
+
+var $abs = require('./abs');
+var $floor = require('./floor');
+
+var $isNaN = require('./isNaN');
+var $isFinite = require('./isFinite');
+
+/** @type {import('./isInteger')} */
+module.exports = function isInteger(argument) {
+	if (typeof argument !== 'number' || $isNaN(argument) || !$isFinite(argument)) {
+		return false;
+	}
+	var absValue = $abs(argument);
+	return $floor(absValue) === absValue;
+};