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>

models/schema/marketplace_import_job.py

@@ -81,6 +81,28 @@ class AdminMarketplaceImportJobRequest(BaseModel):
         return v
 
 
+class MarketplaceImportErrorResponse(BaseModel):
+    """Response schema for individual import error."""
+
+    model_config = ConfigDict(from_attributes=True)
+
+    id: int
+    row_number: int
+    identifier: str | None = None
+    error_type: str
+    error_message: str
+    row_data: dict | None = None
+    created_at: datetime
+
+
+class MarketplaceImportErrorListResponse(BaseModel):
+    """Response schema for list of import errors."""
+
+    errors: list[MarketplaceImportErrorResponse]
+    total: int
+    import_job_id: int
+
+
 class MarketplaceImportJobResponse(BaseModel):
     """Response schema for marketplace import job."""