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>

Cargo.lock

@@ -7050,6 +7050,7 @@ dependencies = [
  "jni 0.21.1",
  "jsonwebtoken",
  "keyring-core",
+ "klondike",
  "reqwest",
  "serde",
  "serde_json",
@@ -7076,6 +7077,7 @@ dependencies = [
  "image",
  "jni 0.21.1",
  "kira",
+ "klondike",
  "reqwest",
  "resvg",
  "ron",
@@ -7135,6 +7137,7 @@ dependencies = [
  "chrono",
  "console_error_panic_hook",
  "getrandom 0.3.4",
+ "klondike",
  "serde",
  "serde-wasm-bindgen",
  "serde_json",