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/escape-string-regexp/index.d.ts

@@ -0,0 +1,18 @@
+/**
+Escape RegExp special characters.
+
+You can also use this to escape a string that is inserted into the middle of a regex, for example, into a character class.
+
+@example
+```
+import escapeStringRegexp = require('escape-string-regexp');
+
+const escapedString = escapeStringRegexp('How much $ for a 🦄?');
+//=> 'How much \\$ for a 🦄\\?'
+
+new RegExp(escapedString);
+```
+*/
+declare const escapeStringRegexp: (string: string) => string;
+
+export = escapeStringRegexp;