Add default v2
Update src/assets/piece/default_v2/black_bishop.png, src/assets/piece/default_v2/black_brawn.png, src/assets/piece/default_v2/black_common_king.png, src/assets/piece/default_v2/black_dragon.png, src/assets/piece/default_v2/black_king.png, src/assets/piece/default_v2/black_knight.png, src/assets/piece/default_v2/black_pawn.png, src/assets/piece/default_v2/black_princess.png, src/assets/piece/default_v2/black_queen.png, src/assets/piece/default_v2/black_rook.png, src/assets/piece/default_v2/black_royal_queen.png, src/assets/piece/default_v2/black_unicorn.png, src/assets/piece/default_v2/white_bishop.png, src/assets/piece/default_v2/white_brawn.png, src/assets/piece/default_v2/white_common_king.png, src/assets/piece/default_v2/white_dragon.png, src/assets/piece/default_v2/white_king.png, src/assets/piece/default_v2/white_knight.png, src/assets/piece/default_v2/white_pawn.png, src/assets/piece/default_v2/white_princess.png, src/assets/piece/default_v2/white_queen.png, src/assets/piece/default_v2/white_rook.png, src/assets/piece/default_v2/white_royal_queen.png, src/assets/piece/default_v2/white_unicorn.png Deleted src/assets/piece/default_v2/.gitkeep