feat(customers): add initial admin bootstrap and csv import

frontend/athena/components/customers/ImportSummaryCard.tsx

@@ -0,0 +1,24 @@
+import type { CustomerImportSummary } from "@/types/customer";
+
+const summaryItems = [
+  ["Gesamt", "total_rows"],
+  ["Gültig", "valid_rows"],
+  ["Fehler", "error_count"],
+  ["Warnungen", "warning_count"],
+  ["Creates", "create_count"],
+  ["Updates", "update_count"],
+  ["Skips", "skip_count"],
+] as const;
+
+export default function ImportSummaryCard({ summary }: { summary: CustomerImportSummary }) {
+  return (
+    <div className="grid grid-cols-2 gap-3 sm:grid-cols-4 lg:grid-cols-7">
+      {summaryItems.map(([label, key]) => (
+        <div key={key} className="rounded-lg border bg-white p-3">
+          <p className="text-xs text-slate-500">{label}</p>
+          <p className="mt-1 text-xl font-semibold text-slate-950">{summary[key]}</p>
+        </div>
+      ))}
+    </div>
+  );
+}