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

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

server/api/product/[slug].get.ts

@@ -0,0 +1,15 @@
+import { fetchCms } from "~/server/utils/cmsApi";
+
+/**
+ * Get product by slug - optimized for SSR.
+ * This route fetches directly from CMS and returns the first matching product.
+ */
+export default defineEventHandler(async (event) => {
+	const slug = getRouterParam(event, "slug");
+	if (!slug) {
+		throw createError({ statusCode: 400, statusMessage: "Missing slug parameter" });
+	}
+
+	const response = await fetchCms<{ data: unknown[] }>(`/products?filters[slug]=${slug}`);
+	return response.data?.[0] ?? null;
+});