feat: replace Forecast tab with Sell-in vs Budget 2026 dashboard

Self-contained view with file upload for Sell in + Budget 26 Excel files.
Parses SKUs (5-digit prefix), compares real sell-in units vs monthly budget
forecast, shows KPIs and per-SKU table sorted by period achievement ascending.

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

App.tsx

@@ -898,21 +898,7 @@ const App: React.FC = () => {
 
               <Suspense fallback={<LoadingSpinner />}>
                 <div className={view === 'forecast' ? '' : 'hidden'}>
-                  <ForecastView
-                    data={forecastData}
-                    filters={filters}
-                    top50Ranking={top50Ranking2025}
-                    stockMap={stockMap}
-                    vendorStockMap={vendorStockMap}
-                    stockFilter={filters.stock}
-                    onStockFilterChange={(s) => setFilters(prev => ({ ...prev, stock: s }))}
-                    vendorStockFilter={filters.vendorStock}
-                    onVendorStockFilterChange={(s) => setFilters(prev => ({ ...prev, vendorStock: s }))}
-                    wocFilter={filters.woc}
-                    onWocFilterChange={(s) => setFilters(prev => ({ ...prev, woc: s }))}
-                    top50Mode={filters.customer.includes('Amazon UK') ? 'uk' : 'eu'}
-                    buyBoxLostMap={buyBoxLostMap}
-                  />
+                  <ForecastView />
                 </div>
               </Suspense>