High-quality mockup of a black t-shirt on a white background, featuring a minimalistic vector design of a small snake coiling around the neckline. The snake should resemble a sleek, chain-like design, subtle and clean. Show both the front and back of the t-shirt, with the fabric being 240gsm for a premium look and feel. The mockup should highlight the t-shirt without any person wearing it, focusing on the garment's structure and design details. Ensure the presentation is elegant and minimal, with the snake design standing out around the collar.