feat: add vendor stock badges to Sell-in vs Budget first column

Shows aggregated EU and UK vendor stock per SKU (sum across all ASINs)
in the first column, matching the style used in other dashboard tabs.

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

App.tsx

@@ -898,7 +898,7 @@ const App: React.FC = () => {
 
               <Suspense fallback={<LoadingSpinner />}>
                 <div className={view === 'forecast' ? '' : 'hidden'}>
-                  <ForecastView asinMetadata={globalAsinMetadata} />
+                  <ForecastView asinMetadata={globalAsinMetadata} vendorStockMap={vendorStockMap} />
                 </div>
               </Suspense>