♻️ (billing) Refactor billing server code to trpc

packages/models/features/billing/invoice.ts

@@ -0,0 +1,11 @@
+import { z } from 'zod'
+
+export const invoiceSchema = z.object({
+  id: z.string(),
+  url: z.string(),
+  amount: z.number(),
+  currency: z.string(),
+  date: z.number().nullable(),
+})
+
+export type Invoice = z.infer<typeof invoiceSchema>