feat: add import error tracking and translation tabs

Import Error Tracking:
- Add MarketplaceImportError model to store detailed error information
- Store row number, identifier, error type, message, and row data for each error
- Add API endpoint GET /admin/marketplace-import-jobs/{job_id}/errors
- Add UI to view and browse import errors in job details modal
- Support pagination and error type filtering

Translation Tabs:
- Replace flat translation list with tabbed interface on product detail page
- Add language tabs with full language names
- Add copy-to-clipboard functionality for translation content
- Improved UX with better visual separation of translations

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

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

app/tasks/background_tasks.py

@@ -73,6 +73,7 @@ async def process_marketplace_import(
             batch_size=batch_size,
             db=db,
             language=language,  # Pass language for translations
+            import_job_id=job_id,  # Pass job ID for error tracking
         )
 
         # Update job with results