refactor: migrate PileType → KlondikePile across core/wasm/engine

- Replace PileType with typed KlondikePile (Foundation/Tableau variants)
  throughout solitaire_core, solitaire_wasm, and solitaire_engine;
  ReplayMove now uses SavedKlondikePile for serialisation stability
- Split replay_overlay.rs into replay_overlay/ module (mod, format,
  input, update, tests) for maintainability
- Add klondike dep to solitaire_engine and solitaire_data Cargo.toml
- Add TestPileState infrastructure to game_state.rs for engine unit tests
- Rebuild solitaire_wasm pkg (js + wasm artefacts updated)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

solitaire_engine/src/animation_plugin.rs

@@ -1078,7 +1078,7 @@ mod tests {
         // Pairs the existing audio (`card_invalid.wav`) and visual
         // (`feedback_anim_plugin::queue_shake_for_rejected_move`) feedback
         // with an accessibility-focused readable text cue.
-        use solitaire_core::pile::PileType;
+        use klondike::{KlondikePile, Tableau};
         let mut app = App::new();
         app.add_plugins(MinimalPlugins).add_plugins(AnimationPlugin);
 
@@ -1090,8 +1090,8 @@ mod tests {
             .count();
 
         app.world_mut().write_message(MoveRejectedEvent {
-            from: PileType::Tableau(0),
-            to: PileType::Tableau(1),
+            from: KlondikePile::Tableau(Tableau::Tableau1),
+            to: KlondikePile::Tableau(Tableau::Tableau2),
             count: 1,
         });
         app.update();