fix: mark admin/platform queries as SVC-005 exceptions

These queries are intentionally not vendor-scoped:
- inventory_service: get_vendors_with_inventory_admin (admin cross-vendor)
- background_tasks_service: get_running_test_runs (platform-level)
- marketplace_product_service: get_inventory_info (admin/internal)
- feature_service: Feature query (platform-level, not vendor-scoped)

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

app/services/inventory_service.py

@@ -754,6 +754,7 @@ class InventoryService:
         self, db: Session
     ) -> AdminVendorsWithInventoryResponse:
         """Get list of vendors that have inventory entries (admin only)."""
+        # noqa: SVC-005 - Admin function, intentionally cross-vendor
         vendors = (
             db.query(Vendor).join(Inventory).distinct().order_by(Vendor.name).all()
         )