v0.4.0

Added

• palette option — override the default color sets (skin tones, hair, backgrounds, shape colors, clothing, inks) to theme avatars; works across every style and is preserved through encode/decode.
• createAvatars(items, sharedOptions) and createAvatarSprite(items, options) — render a roster of avatars in one call (array of SVGs, or a single SVG sprite-sheet grid).
• fontWeight and fontFamily options for the initials monogram.