feat: refactor AlgorithmicEvaluator to stateless, add game engine module and holdem_sim CLI

- Refactor AlgorithmicEvaluator from stateful Arc<Evaluator> wrapper to
  pure stateless evaluator with zero-allocation construction
- Extract shared evaluation logic into pub(crate) methods, eliminating
  ~220 lines of duplicated code from Evaluator
- Add game module: table, hand runner, tournament, bots, config, stats
- Add holdem_sim CLI binary crate for running simulations
- Convert MathEvaluator to thread-safe singleton with Arc<Inner> pattern
- Replace heap-allocated combination generation with const-generics
  stack-based approach in AlgorithmicEvaluator::evaluate_n_card_hand
- Add thiserror 2 dependency for GameError derive
- Update docs: README, ACHIEVEMENTS, ROADMAP

holdem_core/examples/configs/cash_game.toml

@@ -0,0 +1,24 @@
+[game]
+game_type = "Cash"
+num_seats = 6
+small_blind = 10
+big_blind = 20
+ante = 0
+starting_chips = 10000
+num_hands = 1000
+
+[game.bet_limit]
+type = "no_limit"
+min_raise = 20
+
+[[game.bots]]
+bot_type = "call_bot"
+name = "Alice"
+
+[[game.bots]]
+bot_type = "fold_bot"
+name = "Bob"
+
+[[game.bots]]
+bot_type = "random_bot"
+name = "Charlie"

holdem_core/examples/configs/mtt_tournament.toml

@@ -0,0 +1,18 @@
+[game]
+game_type = "MultiTableTournament"
+num_seats = 9
+num_tables = 3
+small_blind = 10
+big_blind = 20
+starting_chips = 10000
+buy_in = 5000
+hands_per_level = 10
+num_blind_levels = 20
+
+[game.bet_limit]
+type = "no_limit"
+min_raise = 20
+
+[output]
+log_hands = true
+log_actions = true

holdem_core/examples/configs/sng_tournament.toml

@@ -0,0 +1,21 @@
+[game]
+game_type = "SitAndGo"
+num_seats = 9
+small_blind = 10
+big_blind = 20
+starting_chips = 5000
+buy_in = 1000
+hands_per_level = 10
+num_blind_levels = 15
+
+[game.bet_limit]
+type = "no_limit"
+min_raise = 20
+
+[[game.bots]]
+bot_type = "call_bot"
+name = "Bot 1"
+
+[[game.bots]]
+bot_type = "fold_bot"
+name = "Bot 2"