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.

app.vue

@@ -0,0 +1,23 @@
+<template>
+	<NuxtLoadingIndicator color="#dc2626" />
+	<NuxtLayout>
+		<NuxtPage />
+	</NuxtLayout>
+</template>
+
+<script setup lang="ts">
+// Initialize cart on app mount (client-side only)
+// Skip on checkout pages that have their own order loading logic
+const route = useRoute();
+const { initialize: initCart } = useCart();
+
+// Pages that manage their own order state and shouldn't have cart auto-init
+const skipCartInitPaths = ["/checkout/3", "/checkout/result"];
+
+onMounted(() => {
+	const shouldSkip = skipCartInitPaths.some((path) => route.path.startsWith(path));
+	if (!shouldSkip) {
+		initCart();
+	}
+});
+</script>