export function hexToRgba(color: string | undefined, alpha: number): string | undefined {
  if (!color) return undefined;
  const hex = color.trim().replace(/^#/, "");
  const normalized =
    hex.length === 3
      ? hex
          .split("")
          .map((c) => c + c)
          .join("")
      : hex;
  if (!/^[0-9a-fA-F]{6}$/.test(normalized)) return undefined;

  const value = Number.parseInt(normalized, 16);
  const r = (value >> 16) & 255;
  const g = (value >> 8) & 255;
  const b = value & 255;
  return `rgba(${r}, ${g}, ${b}, ${alpha})`;
}