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/utils/cmsApi.ts

@@ -0,0 +1,17 @@
+/**
+ * Server-side CMS API utility.
+ * Use this for direct CMS access during SSR.
+ */
+export async function fetchCms<T>(endpoint: string, options: Parameters<typeof $fetch>[1] = {}): Promise<T> {
+	const config = useRuntimeConfig();
+	const url = `${config.cmsInternalUrl}/api${endpoint}`;
+
+	return await $fetch<T>(url, {
+		...options,
+		headers: {
+			"Content-Type": "application/json",
+			Authorization: `Bearer ${config.shopApiToken}`,
+			...((options.headers as Record<string, string>) || {})
+		}
+	});
+}