Phase 3: scaffold Manager Dashboard — all pages, layout, routing

Includes: LoginPage (PIN pad), DashboardPage (30s polling table grid),
OrderDetailPage (full actions), ProductsPage (CRUD + printer zone),
WaitersPage (block/reset PIN/delete), TablesPage, ReportsPage
(shift summary + order history + CSV export), SettingsPage (printers
+ test print + sysadmin lock/unlock). TailwindCSS, React Query,
react-hot-toast. Docker Compose service on port 5174.

manager_dashboard/postcss.config.js

@@ -0,0 +1,3 @@
+export default {
+  plugins: { tailwindcss: {}, autoprefixer: {} },
+}