Rolls dice from standard dice notation for tabletop RPGs. Evaluates XdY, flat modifiers (+/-), and keep-highest / keep-lowest (4d6kh3 for stat rolls, 2d20kh1 / 2d20kl1 for advantage/disadvantage). Returns each individual die, which were kept vs dropped, the per-roll total, and the grand total; roll the whole expression up to 100 times with 'rolls'. Pass 'seed' for reproducible output. Use it as a dice roller API, dice notation evaluator, or tabletop random roll engine.