feat: initial commit — local services (backend + manager dashboard + waiter PWA)

Includes all work to date:
- local_backend: FastAPI backend with products, orders, tables, shifts, cloud sync
- manager_dashboard: React manager UI with product/category management, reports, settings
- waiter_pwa: React PWA for waiter devices
- Category reparent endpoint and UI
- Waiter domain: local_ip sent on heartbeat, waiter_domain persisted from cloud response
- QR code modal in AppInfoTab for waiter domain
- Product form: number input spinners removed, category pre-selected on new product
- Category row: count badge moved to far right

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

manager_dashboard/src/pages/ManagementPage.jsx

@@ -0,0 +1,27 @@
+import { useState } from 'react'
+import { ShoppingBag, LayoutGrid, Users } from 'lucide-react'
+import ProductsTab from './Management/ProductsTab'
+import TablesConfigTab from './TablesConfigTab'
+import StaffTab from './StaffTab'
+import { TabGroup } from '../ui/Tabs'
+
+const TABS = [
+  { id: 'products', label: 'Προϊόντα', icon: ShoppingBag },
+  { id: 'tables',   label: 'Τραπέζια', icon: LayoutGrid },
+  { id: 'staff',    label: 'Προσωπικό', icon: Users },
+]
+
+export default function ManagementPage() {
+  const [activeTab, setActiveTab] = useState('products')
+
+  return (
+    <div className="flex flex-col h-full min-h-0">
+      <TabGroup tabs={TABS} active={activeTab} onChange={setActiveTab} />
+      <div className="flex-1 min-h-0">
+        {activeTab === 'products' && <ProductsTab />}
+        {activeTab === 'tables'   && <TablesConfigTab />}
+        {activeTab === 'staff'    && <StaffTab />}
+      </div>
+    </div>
+  )
+}