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.

components/CookieBanner.vue

@@ -0,0 +1,55 @@
+<template>
+	<div
+		v-if="consentGiven === false"
+		class="fixed bottom-0 left-0 right-0 bg-white border-t border-gray-200 shadow-lg px-4 py-3 text-gray-800 z-50 flex flex-col sm:flex-row sm:items-center sm:justify-between gap-2 sm:gap-4"
+	>
+		<p class="text-xs text-gray-600 sm:flex-1">
+			{{ consentText }}
+		</p>
+
+		<div class="flex items-center gap-2 shrink-0">
+			<Button
+				href="/datenschutz"
+				data-cy="cookie-banner-privacy"
+				classes="bg-transparent border-transparent py-1.5 px-3 !text-xs !text-black hover:!bg-gray-100 shadow-none"
+			>
+				Datenschutzerklärung
+			</Button>
+			<Button @click="acceptCookies" data-cy="cookie-banner-accept" classes="bg-gray-800 py-1.5 px-4 !text-xs whitespace-nowrap">
+				Akzeptieren
+			</Button>
+		</div>
+	</div>
+</template>
+
+<script setup lang="ts">
+const COOKIE_CONSENT_KEY = "shop:cookie-consent";
+
+const props = withDefaults(
+	defineProps<{
+		consentText?: string;
+	}>(),
+	{
+		consentText:
+			"Wir verwenden notwendige Cookies für die sichere Zahlungsabwicklung. Weitere Informationen finden Sie in unserer Datenschutzerklärung:"
+	}
+);
+
+const emit = defineEmits<{
+	"consent-given": [];
+}>();
+
+// Start with null to prevent SSR flash - banner only renders after client check
+const consentGiven = ref<boolean | null>(null);
+
+// Check localStorage only on client
+onMounted(() => {
+	consentGiven.value = !!localStorage.getItem(COOKIE_CONSENT_KEY);
+});
+
+function acceptCookies() {
+	localStorage.setItem(COOKIE_CONSENT_KEY, new Date().toISOString());
+	consentGiven.value = true;
+	emit("consent-given");
+}
+</script>