feat(web): add React Query, dark mode toggle, and error retry UX

- Install @tanstack/react-query with exponential backoff retry config
- Create QueryClientProvider and custom hooks for listings, analytics,
  payments, and subscription API calls
- Migrate 5 dashboard pages from useState/useEffect to React Query hooks
- Add dark mode CSS variables and ThemeProvider with localStorage persistence
- Add theme toggle button in dashboard header (sun/moon icon)
- Enhance error boundaries with auto-retry, retry count, and loading state

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/lib/hooks/use-analytics.ts

@@ -0,0 +1,48 @@
+import { useQuery } from '@tanstack/react-query';
+import { analyticsApi } from '@/lib/analytics-api';
+
+export const analyticsKeys = {
+  all: ['analytics'] as const,
+  marketReport: (city: string, period: string) =>
+    ['analytics', 'market-report', city, period] as const,
+  heatmap: (city: string, period: string) =>
+    ['analytics', 'heatmap', city, period] as const,
+  districtStats: (city: string, period: string) =>
+    ['analytics', 'district-stats', city, period] as const,
+  priceTrend: (district: string, city: string, propertyType: string, periods: string[]) =>
+    ['analytics', 'price-trend', district, city, propertyType, periods] as const,
+};
+
+export function useMarketReport(city: string, period: string) {
+  return useQuery({
+    queryKey: analyticsKeys.marketReport(city, period),
+    queryFn: () => analyticsApi.getMarketReport(city, period),
+  });
+}
+
+export function useHeatmap(city: string, period: string) {
+  return useQuery({
+    queryKey: analyticsKeys.heatmap(city, period),
+    queryFn: () => analyticsApi.getHeatmap(city, period),
+  });
+}
+
+export function useDistrictStats(city: string, period: string) {
+  return useQuery({
+    queryKey: analyticsKeys.districtStats(city, period),
+    queryFn: () => analyticsApi.getDistrictStats(city, period),
+  });
+}
+
+export function usePriceTrend(
+  district: string,
+  city: string,
+  propertyType: string,
+  periods: string[],
+) {
+  return useQuery({
+    queryKey: analyticsKeys.priceTrend(district, city, propertyType, periods),
+    queryFn: () => analyticsApi.getPriceTrend(district, city, propertyType, periods),
+    enabled: !!district && !!city,
+  });
+}