BIT-AIRFLOW-2026-59244 Apache Airflow: Secrets masker: `var.json` Variable values not masked in the Rendered Templates UI

Apache Airflow's secrets masker did not mask var.json Variable values whose value is a dict in the Rendered Templates UI — the dict value failed an isinstancestr guard — so a secret stored as a JSON Variable and referenced in a template via var.json was displayed in cleartext to any user with...