fix: merge history data into rows when products table is empty

src/lib/supabase.ts

@@ -194,6 +194,35 @@ export async function getHistory(): Promise<HistoryEntry[]> {
   }
 }
 
+export async function getHistoryDataForMerge(): Promise<Record<string, ExcelRow>> {
+  try {
+    const response = await safeFetch(
+      `${SUPABASE_URL}/rest/v1/products_history?select=product_id,new_data&order=changed_at.desc`,
+      { cache: 'no-store' }
+    );
+
+    if (!response.ok) {
+      console.error('[getHistoryDataForMerge] Error:', response.status);
+      return {};
+    }
+    const entries: Array<{ product_id: string; new_data: ExcelRow }> = await response.json();
+    
+    const result: Record<string, ExcelRow> = {};
+    const seen = new Set<string>();
+    for (const entry of entries) {
+      if (seen.has(entry.product_id)) continue;
+      seen.add(entry.product_id);
+      if (entry.new_data && entry.new_data.length > 0) {
+        result[entry.product_id] = entry.new_data;
+      }
+    }
+    return result;
+  } catch (error: any) {
+    console.error('[getHistoryDataForMerge] Exception:', error.message);
+    return {};
+  }
+}
+
 export async function deleteHistoryEntry(id: string): Promise<boolean> {
   try {
     const response = await safeFetch(