feat(bm_monitor.py): add logging and graceful shutdown handling

[mauvehed]

Introduce logging to replace print statements, providing better control over log levels and output formatting. This change enhances the ability to debug and monitor the application by logging configuration details and key events. Additionally, implement a signal handler to ensure graceful shutdown on receiving SIGINT or SIGTERM, improving the application's robustness and user experience.

Summary by Sourcery

Add logging and graceful shutdown handling to the Brandmeister monitor.

New Features:

• Log configuration details and key events using configurable log levels and formatting.
• Handle SIGINT and SIGTERM signals to gracefully shut down the application.

[sourcery-ai]

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