refactor(core): move solver to solitaire_data, DrawMode to klondike_adapter, remove pile/solver/schema_version

- Delete solitaire_core::solver — moved wholesale to solitaire_data::solver (re-exported at crate root)
- Delete solitaire_core::pile — no external users
- Move DrawMode from game_state to klondike_adapter; re-export as solitaire_core::DrawMode
- Remove schema_version field from GameState (redundant — deserializer stamps it from the constant)
- Update all callers across solitaire_data, solitaire_engine, solitaire_assetgen, solitaire_wasm

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

Cargo.lock

@@ -7336,11 +7336,13 @@ version = "0.1.0"
 dependencies = [
  "async-trait",
  "axum",
+ "card_game",
  "chrono",
  "dirs",
  "jni 0.21.1",
  "jsonwebtoken",
  "keyring-core",
+ "klondike",
  "reqwest",
  "serde",
  "serde_json",