Fix player rotation bug when all players are in bypass

[NikVince]

When a betting round ends in no-limit hold'em, the game_pointer was being reset unconditionally to (dealer_id + 1) % num_players. If all players were in bypass (folded or all-in), the skip loop wouldn't execute, leaving game_pointer at an incorrect value that could cause the same player to act multiple times in a row.

This fix ensures that game_pointer is only reset when there are active players. If all players are in bypass, the game_pointer from proceed_round() is preserved, allowing the game ending logic to handle it correctly.

Fixes issue where Player 0 (or any player) could act multiple times consecutively after a round ends when all players are in bypass state.

Changes:

• Modified step() method to conditionally reset game_pointer only when there are active players (sum(players_in_bypass) < num_players)
• Added comprehensive tests to verify player rotation works correctly across different dealer positions and round transitions

Tested:

• Added test_player_rotation_no_duplicate_actions() to ensure no player acts twice in a row within the same round
• Added test_player_rotation_round_transition() to verify correct rotation when rounds end across all dealer positions