feat: add ItemOverviewDto for enriched item data in items list

feat: implement CustomerDetailPage for detailed customer view and editing

feat: create CustomersPage for listing and managing customers with filters

feat: add ColumnsMenu component for customizable table columns visibility

feat: implement CSV export functionality for data download

feat: add customer code generation logic for unique customer identifiers

Frontend/erp-system/next.config.ts

@@ -8,7 +8,11 @@ import path from "path"
 //
 // Defaults to the backend's HTTP port: the HTTPS port uses a self-signed dev cert that
 // this proxy would reject.
-const BACKEND_ORIGIN = process.env.BACKEND_ORIGIN ?? "http://localhost:6701"
+//
+// Uses 127.0.0.1, not "localhost": Node resolves "localhost" to the IPv6 loopback (::1)
+// first on this machine, but Kestrel only binds the IPv4 wildcard (0.0.0.0), so every
+// proxied request failed with ECONNREFUSED ::1:6701 until this was pinned to IPv4.
+const BACKEND_ORIGIN = process.env.BACKEND_ORIGIN ?? "http://127.0.0.1:6701"
 
 const nextConfig: NextConfig = {
   turbopack: {