fix: export job records display shows files instead of mixed metrics

Previously export jobs showed "3/23" (languages/products) which was confusing.
Now shows "3/3" (files succeeded / files processed) for consistency.

- Updated log_export to track files_processed/succeeded/failed
- Products count stored in error_details for reference
- Updated documentation to explain records column meaning per job type

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

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

app/services/letzshop_export_service.py

@@ -287,9 +287,10 @@ class LetzshopExportService:
         vendor_id: int,
         started_at: datetime,
         completed_at: datetime,
-        records_processed: int,
-        languages_succeeded: int,
-        languages_failed: int,
+        files_processed: int,
+        files_succeeded: int,
+        files_failed: int,
+        products_exported: int,
         triggered_by: str,
         error_details: dict | None = None,
     ) -> LetzshopSyncLog:
@@ -301,9 +302,10 @@ class LetzshopExportService:
             vendor_id: Vendor ID
             started_at: When the export started
             completed_at: When the export completed
-            records_processed: Number of products exported
-            languages_succeeded: Number of languages successfully exported
-            languages_failed: Number of languages that failed
+            files_processed: Number of language files to export (e.g., 3)
+            files_succeeded: Number of files successfully exported
+            files_failed: Number of files that failed
+            products_exported: Total products in the export
             triggered_by: Who triggered the export (e.g., "admin:123")
             error_details: Optional error details if any failures
 
@@ -314,15 +316,18 @@ class LetzshopExportService:
             vendor_id=vendor_id,
             operation_type="product_export",
             direction="outbound",
-            status="completed" if languages_failed == 0 else "partial",
-            records_processed=records_processed,
-            records_succeeded=languages_succeeded,
-            records_failed=languages_failed,
+            status="completed" if files_failed == 0 else "partial",
+            records_processed=files_processed,
+            records_succeeded=files_succeeded,
+            records_failed=files_failed,
             started_at=started_at,
             completed_at=completed_at,
             duration_seconds=int((completed_at - started_at).total_seconds()),
             triggered_by=triggered_by,
-            error_details=error_details,
+            error_details={
+                "products_exported": products_exported,
+                **(error_details or {}),
+            } if products_exported or error_details else None,
         )
         db.add(sync_log)
         db.flush()