* Fix: Prevent side effects in `processMCPEnv` by deep cloning MCPOptions
The `processMCPEnv` function was modifying the original `MCPOptions` object, leading to unintended side effects where `LIBRECHAT_USER_ID` could be incorrectly shared across different users. This commit addresses this issue by performing a deep clone of the `MCPOptions` object before processing, ensuring that modifications are isolated and do not affect other users.
* ci: Add tests for processMCPEnv to ensure deep cloning, user ID isolation and environment variable processing
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Co-authored-by: Alex C <viennadd@users.noreply.github.com>
* refactor: use new image output format for agents using DALL-E tools
* refactor: Enhance image fetching with proxy support and adjust logging placement in DALL-E 3 integration
* refactor: Enhance StableDiffusionAPI to support agent-specific return values and display message for generated images
* refactor: Add unit test execution for librechat-mcp in backend review workflow
* refactor: Update environment variable extraction logic, export from serpate module to avoid circular refs, and remove deprecated tests
* refactor: Add unit tests for environment variable extraction and enhance StdioOptionsSchema to process env variables
