Detect ASIN column index dynamically from headers

src/App.tsx

@@ -77,6 +77,14 @@ export default function App() {
           const rawHeaders = data[0];
           const rawRows = data.slice(1);
 
+          // Find ASIN column index from headers (case insensitive)
+          const asinIdx = (rawHeaders as string[]).findIndex((h: string) => 
+            String(h).toLowerCase().trim() === 'asin'
+          );
+          if (asinIdx !== -1) {
+            console.log('ASIN column found at index:', asinIdx);
+          }
+
           console.log('Applying Supabase overrides...');
           const syncedData = await getAllSyncedRows();
           const articleNoIdx = COLUMNS.ARTICLE_NO;