"Adapt this muffin recipe to be fully vegan, celiac-friendly (gluten-free), nut-free, and lower in sugar while keeping metric measurements. Keep the recipe as blueberry chocolate chip muffins. Replace eggs, dairy milk, and butter with vegan alternatives; replace all-purpose flour with a reliable gluten-free flour blend suitable for muffins; reduce the sugar to a moderate amount without making the muffins bland; ensure all ingredients and instructions are safe for celiac disease and nut-free. Provide a complete recipe with ingredients and step-by-step instructions in metric units only."