Sandbox streams reconnect on EOF; Dockerfile snapshots now supported

What's Changed

• fix: reconnect sandbox command streams on EOF by @ramon-langchain in https://github.com/langchain-ai/langsmith-sdk/pull/2941
• feat(sandbox): build snapshots from Dockerfiles by @langchain-infra in https://github.com/langchain-ai/langsmith-sdk/pull/2950
• fix(python): add organization id to context URLs by @vishnu-ssuresh in https://github.com/langchain-ai/langsmith-sdk/pull/2945
• fix(js): add organization id to context URLs by @vishnu-ssuresh in https://github.com/langchain-ai/langsmith-sdk/pull/2946
• release(py): 0.8.7 by @ramon-langchain in https://github.com/langchain-ai/langsmith-sdk/pull/2947

Full Changelog: https://github.com/langchain-ai/langsmith-sdk/compare/v0.8.6...v0.8.7