feat: add automatic database import after ERP data extraction

- Add DataImportService for reading Excel and importing to database
- Extend DiscreteMaterialPlanDAO with deleteBySourceNumbers and batchInsert
- Auto-trigger database write after successful Excel merge
- Support batch delete by SourceNumber and batch insert (1000/batch)
- Update ExtractorPage UI to show import results
- Fix SQL Server query to handle undefined recordset for DELETE/INSERT

Co-Authored-By: Claude (glm-5) <noreply@anthropic.com>

src/main/services/database/sql-server.ts

@@ -92,8 +92,8 @@ export class SqlServerService implements IDatabaseService {
 
       const result = await request.query(sqlString)
 
-      // Convert recordset to array of objects
-      const rows = result.recordset as Record<string, unknown>[]
+      // Convert recordset to array of objects (may be undefined for DELETE/INSERT/UPDATE)
+      const rows = (result.recordset as Record<string, unknown>[]) || []
       // Extract column names from the first row if available
       const columns = rows.length > 0 ? Object.keys(rows[0]) : []