fix: proper game graphics — chess SVG pieces, ludo cross board, domino felt table

- Chess: vector piece paths (king, queen, rook, bishop, knight, pawn) rendered
  as proper filled shapes with stroke, not unicode characters
- Ludo: actual cross-shaped board with colored home zones, triangular center,
  home columns, and round pieces with highlights
- Domino: green felt table background, proper tiles with pip dots rendered
  correctly for each value, ivory tile color with borders
Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>