Flyto2 Core: ${env.VAR} interpolation reads any env secret despite env.get being denylisted

Flyto2 Core is an execution kernel for automation and AI-agent workflows. Prior to 2.26.6, the workflow engine variable resolver expands ${env.VAR} for any host environment variable without an allowlist or capability policy check, allowing a workflow parameter to bypass the default capability policy denylist for env.get and env.load_dotenv and exfiltrate secrets through allowed modules. This issue is fixed in version 2.26.6.