feat: integrate Glance Views (GV) from Traffic Weekly.xlsx

- types.ts: Added TrafficRecord interface and glanceViews field to CombinedKPIs
- dataProcessor.ts: Added processTrafficExcel parser for Traffic Weekly.xlsx
- dataProcessor.ts: Updated mergeSalesAndAdsData to accept and merge traffic data
- App.tsx: Added trafficData state and handleTrafficUpload handler
- FileUpload.tsx: Added Traffic file upload section for GV data
- AdsPerformance.tsx: Added GV and CVR(GV) summary cards
- AdsPerformance.tsx: Added GV column to product table

types.ts

@@ -150,6 +150,14 @@ export interface AdsRecord {
   attributedSales30d: number;
 }
 
+export interface TrafficRecord {
+  country: string;       // Marketplace (DE, UK, etc.)
+  year: number;
+  week: number;
+  asin: string;
+  glanceViews: number;   // Page views
+}
+
 export interface CombinedKPIs {
   id: string;
   marketplace: string;
@@ -184,4 +192,5 @@ export interface CombinedKPIs {
   ctr: number;
   cpc: number;
   cvrUnits: number;
+  glanceViews: number;   // Traffic / page views
 }