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

docs/ROADMAP.md

@@ -16,25 +16,30 @@
 - Game type configurations (Cash/SNG/MTT, buyins, blinds, hands per level, etc.)
 - Simulation parameters (hands/tournaments count, buyin thresholds for bots, etc.)
 
-### Phase 2: Simulation Testbed
+### Phase 2: Simulation Testbed ✅
 **Goal:** Mass simulation capability
 
-**Testbed core**
-- Tournament/cash game runners
-- Parallel simulation engine
-- Result collection and analysis
-- Bot interface with early folding capability
-- Bot performance metrics & visualization
-- Simulation and game factories
-- Configuration-driven experiment runner
+**Testbed core** ✅
+- Tournament/cash game runners ✅
+- Result collection and analysis ✅
+- Bot interface with early folding capability ✅
+- Bot performance metrics & summary ✅
+- Simulation and game factories ✅
+- Configuration-driven experiment runner ✅
+- Seed control for reproducibility ✅
+
+**Remaining for mass simulation**
+- Parallel simulation engine (multi-threading)
+- Result visualization (charts/graphs)
+- Rebuy/addon support for tournaments
 
 ---
 
 ### Phase 3: Bot Framework
 **Goal:** All bot types with playability enhancement
 
-**Bot core implementations**
-- Generic helper functions for strategies
+**Bot core implementations** (partially complete — basic bots exist)
+- ~~Generic helper functions for strategies~~ (basic bots done: CallBot, FoldBot, RaiseBot, RandomBot)
 - Modular Strategy per stage and game situation
 - Rule-based bot with configurable thresholds – port from Java
 - Nash equilibrium calculator for SNG endgame – port from Java