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>

waiter_pwa/src/store/connectionStore.js

@@ -0,0 +1,33 @@
+import { create } from 'zustand'
+
+/**
+ * Tracks the live connection state and emergency mode flag.
+ *
+ * States:
+ *   'online'     — server reachable, SSE connected, normal operation
+ *   'lost'       — server unreachable, modal shown (Wait / Emergency)
+ *   'emergency'  — user chose emergency mode, working from IndexedDB snapshot
+ */
+const useConnectionStore = create((set, get) => ({
+  status: 'online',       // 'online' | 'lost' | 'emergency'
+  lostAt: null,           // Date when connection was lost
+
+  setLost: () => {
+    if (get().status === 'online') {
+      set({ status: 'lost', lostAt: new Date() })
+    }
+  },
+
+  setOnline: () => set({ status: 'online', lostAt: null }),
+
+  enterEmergency: () => set({ status: 'emergency' }),
+
+  // Called when server comes back while in emergency mode — triggers sync then go online
+  exitEmergency: () => set({ status: 'online', lostAt: null }),
+
+  isOnline:    () => get().status === 'online',
+  isLost:      () => get().status === 'lost',
+  isEmergency: () => get().status === 'emergency',
+}))
+
+export default useConnectionStore