Client.close() releases sessions; multipart streaming now configurable

What's Changed

• release(js): 0.7.0 by @ramon-langchain in https://github.com/langchain-ai/langsmith-sdk/pull/2890
• fix(js): add alias for experimental/sandbox to appease broad peer dep range within deepagents by @dqbd in https://github.com/langchain-ai/langsmith-sdk/pull/2893
• feat(js): allow disabling multipart streaming via env variable by @dqbd in https://github.com/langchain-ai/langsmith-sdk/pull/2900
• feat(python): add Client.close() to release session [closes LSDK-183] by @open-swe[bot] in https://github.com/langchain-ai/langsmith-sdk/pull/2866
• feat(sandbox): forward client default headers on exec WebSocket by @open-swe[bot] in https://github.com/langchain-ai/langsmith-sdk/pull/2899
• release(js): 0.7.1 by @langchain-infra in https://github.com/langchain-ai/langsmith-sdk/pull/2902
• release(py): 0.8.5 by @langchain-infra in https://github.com/langchain-ai/langsmith-sdk/pull/2903

Full Changelog: https://github.com/langchain-ai/langsmith-sdk/compare/v0.8.4...v0.8.5