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_core/src/klondike_adapter.rs

@@ -22,7 +22,6 @@ use klondike::{
 use serde::{Deserialize, Serialize};
 
 use crate::game_state::{DrawMode, GameMode};
-use crate::pile::PileType;
 
 /// Bridges `solitaire_core` game config and scoring to the upstream `klondike` crate.
 ///
@@ -97,12 +96,12 @@ impl KlondikeAdapter {
     /// - Waste → Tableau: +5
     /// - Foundation → Tableau: −15
     /// - All other moves: 0
-    pub fn score_for_move(&self, from: &PileType, to: &PileType) -> i32 {
+    pub fn score_for_move(&self, from: &KlondikePile, to: &KlondikePile) -> i32 {
         let sc = &self.config.scoring;
         match (from, to) {
-            (_, PileType::Foundation(_)) => sc.move_to_foundation,
-            (PileType::Waste, PileType::Tableau(_)) => sc.move_to_tableau,
-            (PileType::Foundation(_), PileType::Tableau(_)) => sc.move_from_foundation,
+            (_, KlondikePile::Foundation(_)) => sc.move_to_foundation,
+            (KlondikePile::Stock, KlondikePile::Tableau(_)) => sc.move_to_tableau,
+            (KlondikePile::Foundation(_), KlondikePile::Tableau(_)) => sc.move_from_foundation,
             _ => 0,
         }
     }
@@ -146,7 +145,12 @@ impl KlondikeAdapter {
     /// Score delta for a card move, accounting for game mode.
     ///
     /// Returns 0 in [`GameMode::Zen`] (all scoring suppressed).
-    pub fn score_for_move_with_mode(&self, from: &PileType, to: &PileType, mode: GameMode) -> i32 {
+    pub fn score_for_move_with_mode(
+        &self,
+        from: &KlondikePile,
+        to: &KlondikePile,
+        mode: GameMode,
+    ) -> i32 {
         if mode == GameMode::Zen { 0 } else { self.score_for_move(from, to) }
     }