🧹 [code health] Refactor MessageBroadcaster parameters to dataclass

[marko1olo]

🎯 What: Refactored MessageBroadcaster and send_message_to_users to use a BroadcastConfig dataclass instead of 12 individual arguments.
💡 Why: Reduces the number of parameters and improves maintainability and readability, addressing pylint R0913 (Too many arguments) at main.py:4820.
✅ Verification: Ran pylint and tests, which successfully executed without R0913 errors for these functions.
✨ Result: A more readable and maintainable codebase.

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PR created automatically by Jules for task 411713297602839658 started by @marko1olo

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