🐛 Improve cleanup process in closeEvent to ensure proper resource release and thread management

[GiulioRomualdi]

Without this fix the application segsfaults when closing it if the matfile is loaded. The regression was introduced in #104

[Copilot]

Pull Request Overview

This PR fixes a segmentation fault that occurs when closing the application with a matfile loaded by improving the cleanup process in the closeEvent method. The fix addresses the regression introduced in PR #104 by implementing a more systematic approach to resource cleanup and thread management.

• Implements proper signal disconnection to prevent callbacks during UI teardown
• Adds graceful shutdown for worker threads and multimedia resources
• Introduces explicit resource cleanup with proper error handling

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[Copilot]

Catching Exception is too broad and can mask unexpected errors. Consider catching specific exceptions like RuntimeError or AttributeError that are expected during cleanup operations.

Suggested change

	except Exception:
	except (RuntimeError, AttributeError):

[Copilot]

[nitpick] The check for video_item.media_loaded before calling media_player.stop() may not be necessary during cleanup. Consider calling stop() unconditionally as it should be safe to call on a stopped player.

Suggested change

	if video_item.media_loaded:
	media_player.stop()
	media_player.stop()