Always forbid bids that add up to the cards in hand

The sum of all bids may never equal the number of cards each player
holds in the round; the last bidder has to adjust their bid. This was an
optional "not equal" lobby setting and is now a fixed rule of the game
engine, so it applies to humans, AI players and training alike.

- Remove GameOptions.not_equal, the set_options field, the lobby toggle
  and the --not-equal training flag
- Explain the rule in the lobby and show the blocked bid while bidding
- Drop the option from the AI observation encoding
- Tests check that no round ends with bids summing to the cards in hand

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

wizard_ai/tests/test_ai.py

@@ -30,7 +30,7 @@ def test_action_space_round_trip():
 
 @pytest.mark.parametrize("agent", [HeuristicAgent(), RandomAgent(1), ModelAgent(UniformPolicy(1))])
 def test_agents_play_legal_games(agent):
-    game = WizardGame(4, GameOptions(not_equal=True), seed=3)
+    game = WizardGame(4, seed=3)
     while not game.is_finished:
         obs = game.observation(game.current_player)
         action = agent.act(obs)