feat(dashboard) admin 3.0 return creation (#6713)

**What**
- request return flow

Co-authored-by: Kasper Fabricius Kristensen <45367945+kasperkristensen@users.noreply.github.com>

packages/admin-next/dashboard/src/lib/cast-number.ts

@@ -0,0 +1,6 @@
+/**
+ * Helper function to cast a z.union([z.number(), z.string()]) to a number
+ */
+export const castNumber = (number: number | string) => {
+  return typeof number === "string" ? Number(number.replace(",", ".")) : number
+}