🧹 [Refactor send_message_to_users to use BroadcastConfig]

[marko1olo]

🎯 What: Refactored send_message_to_users and MessageBroadcaster to use a single BroadcastConfig dataclass instead of a long list of parameters.
💡 Why: Fixes code health issue 'Too Many Parameters' making the function signatures cleaner, preventing argument order mistakes, and making it easier to maintain and extend in the future.
✅ Verification: Validated syntax with py_compile, checked local isolated test specifically for send_message_to_users configuration parsing, and ensured temporary files were deleted.
✨ Result: Improved readability and maintainability of the core message broadcasting functions without altering their underlying behavior.

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PR created automatically by Jules for task 11351185253934353842 started by @marko1olo

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