This pull request introduces several improvements and refactorings related to pin connection logic and board iteration in the flow system. The main focus is on making pin lookup and cleanup logic more robust and maintainable, as well as enhancing debugging capabilities.

Pin connection and cleanup logic improvements

• Refactored the main_pin_iteration method in FixPinsCleanup to use a single lookup for the owner parent ID, simplifying and improving the reliability of pin connection and dependency cleanup. The code now handles both connected and missing pins more consistently.
• Removed unnecessary cleanup of old dependencies when connecting pins in connect_pins, streamlining the update process for pin dependencies and connections.

Board iteration and pin lookup enhancements

• Updated the board's pin lookup logic to search across all layers, ensuring that pins can be found even if they are not directly associated with a node. This increases the robustness of pin retrieval.

Debugging and code clarity improvements

• Added the Debug trait to the NodeOrLayer enum to facilitate easier debugging and logging.
• Removed the unused is_node method from the NodeOrLayer enum for improved code clarity.