feat: add job details modal for Letzshop jobs tab

- Replace browser alert with proper modal for job details view
- Show job info, status, records, timestamps in modal
- Display export file details (languages, file sizes) for export jobs
- Include error_details in API response for export and order_sync jobs
- Add selectedJobDetails state and showJobDetailsModal flag

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

app/services/letzshop/order_service.py

@@ -705,6 +705,7 @@ class LetzshopOrderService:
                         "records_processed": log.records_processed or 0,
                         "records_succeeded": log.records_succeeded or 0,
                         "records_failed": log.records_failed or 0,
+                        "error_details": log.error_details,
                     }
                 )
 
@@ -733,6 +734,7 @@ class LetzshopOrderService:
                         "records_processed": log.records_processed or 0,
                         "records_succeeded": log.records_succeeded or 0,
                         "records_failed": log.records_failed or 0,
+                        "error_details": log.error_details,  # Include export file details
                     }
                 )