feat: implement Ads Performance tab

- types.ts: Add conversions field to CombinedKPIs
- dataProcessor.ts: Populate conversions in mergeSalesAndAdsData
- AdsPerformance.tsx: New component with aggregated advertising metrics and detailed product table
- App.tsx: Add Ads view to switcher and render AdsPerformance component
- Icons.tsx: Added icon support for the new Ads tab

types.ts

@@ -170,6 +170,7 @@ export interface CombinedKPIs {
   cost: number;
   clicks: number;
   impressions: number;
+  conversions: number;
 
   salesOrganic: number;
   unitsOrganic: number;