Create custom nodes

This endpoint registers new node kinds along with optional display metadata such as icons and colors. The provided configuration controls how nodes of the specified kinds are interpreted and rendered in the UI. Only free, solid-style Font Awesome icons are supported. Hex color codes must follow the format #RGB or #RRGGBB. If no valid icon or color is provided, the system will fall back to a question mark icon and a white background color. Batch input is supported; you may submit multiple configuration objects in a single request.