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/game_plugin.rs

@@ -14,8 +14,8 @@ use bevy::prelude::*;
 use bevy::tasks::{AsyncComputeTaskPool, Task, futures_lite::future};
 use bevy::window::AppLifecycle;
 use solitaire_core::KlondikePile;
-use solitaire_core::game_state::{DrawMode, GameMode, GameState};
-use solitaire_core::solver::{SolverConfig, SolverResult, try_solve};
+use solitaire_core::{DrawMode, game_state::{GameMode, GameState}};
+use solitaire_data::solver::{SolverConfig, SolverResult, try_solve};
 #[allow(deprecated)]
 use solitaire_data::latest_replay_path;
 use solitaire_data::{
@@ -316,7 +316,7 @@ fn seed_from_system_time() -> u64 {
 }
 
 /// Walks forward from `initial_seed` (incrementing by 1 with wrapping
-/// arithmetic) until the [`solitaire_core::solver`] returns a verdict
+/// arithmetic) until the [`solitaire_data::solver`] returns a verdict
 /// the engine accepts as winnable, or until [`SOLVER_DEAL_RETRY_CAP`]
 /// attempts have elapsed.
 ///