feat: tournament rake, percentage-based prizes, and finish position fixes

- Add tournament_rake_percentage field to GameConfig (house share of entry fees)
- Convert prize structure from absolute amounts to percentages of prize pool
- Fix finish position calculation for tournament eliminations (was inverted)
- Add batch bustout processing for multi-table tournaments (shared positions)
- Add max_rebuys field and rebuy_count tracking on Seat
- Add PrizeStructure::with_rake() and rake_amount field
- Accumulate stats across tournament series (hands, rake, profit)
- Add best_finish and prize_won fields to PlayerStats
- Replace floating-point prize math with integer arithmetic (chip conservation)
- Add comprehensive tests for prize distribution and finish positions
- Update config examples to use percentage-based prizes with rake
- Add ARCHITECTURE_TOURNAMENT_RAKE.md documentation

holdem_sim/src/main.rs

@@ -161,11 +161,12 @@ fn run_tournament_simulation(config: &holdem_core::game::config::GameConfig) {
         _ => unreachable!(),
     };
 
-    // Warn if seed was requested but cannot be applied to tournaments yet
+    // Warn if seed was requested but cannot be applied to single-tournament runs
     if config.seed.is_some() {
         eprintln!(
-            "Warning: seed is not yet supported for tournament simulations; \
-             results will not be reproducible."
+            "Warning: seed is not supported for single-tournament runs; \
+             results will not be reproducible. Use num_tournaments > 1 for \
+             reproducible series."
         );
     }