feat: extract cms from mp/cms — initial libreshop/cms

Source moved verbatim from mp/cms/ on 2026-04-29; mp was the first
concrete adapter consuming the libreshop toolkit. Builds and publishes
git.librete.ch/libreshop/cms on every main / v* push via the standard
.gitea/workflows/build.yml shared across libreshop components.

src/api/customer/routes/customer.ts

@@ -0,0 +1,7 @@
+/**
+ * customer router
+ */
+
+import { factories } from "@strapi/strapi";
+
+export default factories.createCoreRouter("api::customer.customer");