PYSEC-2026-2560 LangSmith SDK: Public prompt pull deserializes untrusted manifests without trust boundary warning

Description The LangSmith SDK's prompt pull methods pullprompt / pullpromptcommit in Python, pullPrompt / pullPromptCommit in JS/TS fetch and deserialize prompt manifests from the LangSmith Hub. These manifests may contain serialized LangChain objects and model configuration that affect runtime...