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>

solitaire_core/src/lib.rs

@@ -3,8 +3,6 @@ pub mod card;
 pub mod error;
 pub mod game_state;
 pub mod klondike_adapter;
-pub mod pile;
-pub mod solver;
 
 // Re-export the upstream types that cross the solitaire_core API boundary so
 // downstream crates (engine, wasm) can import from one place without a direct
@@ -15,6 +13,7 @@ pub mod solver;
 // not appear in any public method signature.
 pub use card_game::Session;
 pub use klondike::{Foundation, Klondike, KlondikePile, Tableau};
+pub use klondike_adapter::DrawMode;
 
 #[cfg(test)]
 mod proptest_tests;