chore: import upstream snapshot with attribution

apps/webapp/app/services/promoCode.server.ts

@@ -0,0 +1,26 @@
+import { createCookie } from "@remix-run/node";
+import { env } from "~/env.server";
+
+// Carries a promo code from the landing page through signup to first-org
+// creation. httpOnly + sameSite=lax so it survives the OAuth round-trip,
+// matching the existing redirect-to cookie.
+export const promoCodeCookie = createCookie("promo-code", {
+  maxAge: 60 * 60, // 1 hour — enough to complete signup
+  httpOnly: true,
+  sameSite: "lax",
+  secure: env.NODE_ENV === "production",
+  path: "/",
+});
+
+export async function setPromoCodeCookie(code: string): Promise<string> {
+  return await promoCodeCookie.serialize(code);
+}
+
+export async function getPromoCodeFromCookie(request: Request): Promise<string | null> {
+  const value = await promoCodeCookie.parse(request.headers.get("Cookie"));
+  return typeof value === "string" && value.length > 0 ? value : null;
+}
+
+export async function clearPromoCodeCookie(): Promise<string> {
+  return await promoCodeCookie.serialize("", { maxAge: 0 });
+}