restore_user_tracing_api_keys

Restore caller tracing API keys in an environment passed to user code.

Reverts both bootstrap overwrites of the canonical LangSmith key the DEEPAGENTS_CODE_-prefixed override and the /auth-stored key so shell subprocesses receive the caller's own key rather than the agent's session key. See original_tracing_api_keys for the rationale; this mirrors restore_user_tracing_env, which does the same for tracing flags.