feat: major dashboard & waiter PWA overhaul

- Manager dashboard: replaced monolithic DashboardTab/OperationsPage with new
  DashboardPage; added OrderDetailModal, ShiftDetailModal, DeleteConfirmModal,
  PaymentMethodModal; updated Sidebar routing and App navigation
- Reports: reworked WorkDaySummary, OrderHistory, ShiftsOverview with detail modals
- Backend routers: extended orders, reports, shifts, products, business_day endpoints;
  updated cloud_sync service
- Waiter PWA: refreshed app icons, improved ConnectionLostModal UX, updated
  TableCard, SSEContext, connectionStore; added useProductCache hook; vite config tweaks

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

waiter_pwa/src/hooks/useProductCache.js

@@ -0,0 +1,69 @@
+import { useQuery, useQueryClient } from '@tanstack/react-query'
+import { useEffect } from 'react'
+import client from '../api/client'
+import db from '../db/posdb'
+
+export const PRODUCTS_KEY = ['products']
+export const CATEGORIES_KEY = ['categories']
+
+async function fetchAndCacheProducts() {
+  const [prodRes, catRes] = await Promise.all([
+    client.get('/api/products/'),
+    client.get('/api/products/categories'),
+  ])
+  const products = prodRes.data
+  const categories = catRes.data
+
+  // Write to IndexedDB in the background — don't await so UI isn't blocked
+  db.products.bulkPut(products).catch(() => {})
+  db.categories.bulkPut(categories).catch(() => {})
+
+  return { products, categories }
+}
+
+async function loadFromCache() {
+  const [products, categories] = await Promise.all([
+    db.products.toArray(),
+    db.categories.toArray(),
+  ])
+  if (products.length === 0 && categories.length === 0) return null
+  return { products, categories }
+}
+
+export function useProductCache() {
+  const queryClient = useQueryClient()
+
+  const query = useQuery({
+    queryKey: PRODUCTS_KEY,
+    queryFn: fetchAndCacheProducts,
+    // Serve stale data instantly — products don't change every second
+    staleTime: 5 * 60 * 1000,      // 5 min before background re-fetch
+    gcTime: 60 * 60 * 1000,        // keep in memory for 1 hour
+    placeholderData: undefined,
+  })
+
+  // On mount, if the query has no data yet, seed it from IndexedDB immediately
+  // so the UI renders without waiting for the network round-trip
+  useEffect(() => {
+    const cached = queryClient.getQueryData(PRODUCTS_KEY)
+    if (cached) return
+
+    loadFromCache().then(idbData => {
+      if (idbData) {
+        // Set as placeholder — React Query will still fetch in background
+        queryClient.setQueryData(PRODUCTS_KEY, idbData)
+      }
+    })
+  }, [queryClient])
+
+  return {
+    products:   query.data?.products   ?? [],
+    categories: query.data?.categories ?? [],
+    isLoading:  query.isLoading && !query.data,
+  }
+}
+
+// Call this from SSEContext when products_changed arrives
+export function invalidateProductCache(queryClient) {
+  queryClient.invalidateQueries({ queryKey: PRODUCTS_KEY })
+}