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_data/Cargo.toml

@@ -16,6 +16,7 @@ dirs           = { workspace = true }
 reqwest        = { workspace = true }
 tokio          = { workspace = true }
 uuid           = { workspace = true }
+klondike       = { workspace = true }
 
 # `keyring-core` is the typed Entry/Error API used by
 # `auth_tokens`. The crate's own dependency tree pulls in

solitaire_data/src/replay.rs

@@ -27,7 +27,7 @@ use std::path::{Path, PathBuf};
 use chrono::NaiveDate;
 use serde::{Deserialize, Serialize};
 use solitaire_core::game_state::{DrawMode, GameMode};
-use solitaire_core::pile::PileType;
+use solitaire_core::klondike_adapter::SavedKlondikePile;
 
 const LATEST_REPLAY_FILE_NAME: &str = "latest_replay.json";
 const REPLAY_HISTORY_FILE_NAME: &str = "replays.json";
@@ -96,9 +96,9 @@ pub enum ReplayMove {
     /// A successful `move_cards(from, to, count)` call.
     Move {
         /// Source pile.
-        from: PileType,
+        from: SavedKlondikePile,
         /// Destination pile.
-        to: PileType,
+        to: SavedKlondikePile,
         /// Number of cards moved.
         count: usize,
     },
@@ -442,6 +442,7 @@ pub fn migrate_legacy_latest_replay(latest_path: &Path, history_path: &Path) {
 #[allow(deprecated)]
 mod tests {
     use super::*;
+    use solitaire_core::klondike_adapter::{SavedFoundation, SavedTableau};
     use std::env;
 
     fn tmp_path(name: &str) -> PathBuf {
@@ -460,14 +461,14 @@ mod tests {
             vec![
                 ReplayMove::StockClick,
                 ReplayMove::Move {
-                    from: PileType::Waste,
-                    to: PileType::Tableau(3),
+                    from: SavedKlondikePile::Stock,
+                    to: SavedKlondikePile::Tableau(SavedTableau(3)),
                     count: 1,
                 },
                 ReplayMove::StockClick,
                 ReplayMove::Move {
-                    from: PileType::Tableau(3),
-                    to: PileType::Foundation(0),
+                    from: SavedKlondikePile::Tableau(SavedTableau(3)),
+                    to: SavedKlondikePile::Foundation(SavedFoundation(0)),
                     count: 1,
                 },
             ],