미니멀 흑백 프로세스 순서도

A minimalist, technical process flowchart diagram depicting [a user authentication and checkout flow]. Ultra-clean vector schematic style on a pure solid white background. Nodes and shapes: start and end nodes are clean capsule shapes; action steps are crisp rounded rectangles with subtle rounded corners; decision points are sharp diamonds. All shapes have a pure white fill with thin 1px dark gray outlines. Connectors: strictly orthogonal elbow lines with precise 90-degree right angles, ending in small solid black triangular arrowheads. Typography: neat, centered dark gray sans-serif labels inside each node, perfectly aligned and organized like professional software documentation.