fix: correct service methods and add inventory schema model

Services:
- admin_service: Add source_url to import job response, fix vendor_name
  to use vendor.name relationship instead of vendor_name field
- marketplace_product_service: Include reserved_quantity and
  available_quantity in InventoryLocationResponse
- vendor_service: Fix _get_product_by_id_or_raise to use database ID
  (int) instead of marketplace_product_id (str)

Schema:
- Add InventorySummaryResponse model for marketplace product service

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

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

app/services/admin_service.py

@@ -845,9 +845,10 @@ class AdminService:
             job_id=job.id,
             status=job.status,
             marketplace=job.marketplace,
+            source_url=job.source_url,
             vendor_id=job.vendor.id if job.vendor else None,
             vendor_code=job.vendor.vendor_code if job.vendor else None,
-            vendor_name=job.vendor_name,
+            vendor_name=job.vendor.name if job.vendor else None,
             imported=job.imported_count or 0,
             updated=job.updated_count or 0,
             total_processed=job.total_processed or 0,