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_engine/src/pending_hint.rs

@@ -28,7 +28,7 @@ use bevy::prelude::*;
 use bevy::tasks::{AsyncComputeTaskPool, Task, futures_lite::future};
 use solitaire_core::KlondikePile;
 use solitaire_core::game_state::GameState;
-use solitaire_core::solver::{SolverConfig, SolverResult, try_solve_from_state};
+use solitaire_data::solver::{SolverConfig, SolverResult, try_solve_from_state};
 
 use crate::card_plugin::CardEntity;
 use crate::events::{HintVisualEvent, InfoToastEvent, StateChangedEvent};
@@ -188,7 +188,7 @@ mod tests {
     use crate::input_plugin::HintSolverConfig;
     use solitaire_core::{Foundation, Tableau};
     use solitaire_core::card::{Card, Rank, Suit};
-    use solitaire_core::game_state::{DrawMode, GameState};
+    use solitaire_core::{DrawMode, game_state::GameState};
 
     /// Build a minimal Bevy app exercising only the polling system
     /// and the resources/messages it touches.