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/ACHIEVEMENTS.md

@@ -8,6 +8,32 @@
 - Card/Hand/Board representations ✅
 - Fast LUT hand evaluator (5, 6, and 7 cards) ✅
 
+### Phase 2: Simulation Testbed ✅
+
+**Bot framework**
+- Meerkat-API-compatible `HoldemPlayer` trait ✅
+- Built-in bots: CallBot, FoldBot, RaiseBot, RandomBot ✅
+- Bot factory for config-driven bot instantiation ✅
+
+**Game engine**
+- Full hand execution engine (HandRunner state machine) ✅
+- Table management with seating, button rotation, blind posting ✅
+- Tournament support (SNG, MTT) with blind schedules and prize structures ✅
+- Pot management with side pot algorithm ✅
+- NL/PL/FL betting structures ✅
+- Seed control for reproducible simulations ✅
+
+**Simulation infrastructure**
+- TOML-based configuration system ✅
+- Cash game simulation loop ✅
+- Performance statistics accumulator ✅
+- CLI simulation runner (`holdem_sim`) ✅
+- Example configs for Cash, SNG, and MTT ✅
+
+**Testing**
+- 369+ unit tests passing ✅
+- Integration and property tests ✅
+
 ## Success Metrics
 
 - **Bot Performance:** Profitability across different game types