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/settings_plugin.rs

@@ -15,7 +15,7 @@ use bevy::input::mouse::{MouseScrollUnit, MouseWheel};
 use bevy::prelude::*;
 use bevy::ui::{ComputedNode, UiGlobalTransform};
 use bevy::window::{WindowMoved, WindowResized};
-use solitaire_core::game_state::DrawMode;
+use solitaire_core::DrawMode;
 use solitaire_data::{
     AnimSpeed, REPLAY_MOVE_INTERVAL_STEP_SECS, Settings, TIME_BONUS_MULTIPLIER_STEP,
     TOOLTIP_DELAY_STEP_SECS, WindowGeometry, load_settings_from, save_settings_to, settings::Theme,
@@ -241,7 +241,7 @@ enum SettingsButton {
     ToggleTouchInputMode,
     /// Toggle the [`Settings::winnable_deals_only`] flag. When on, new
     /// random Classic-mode deals are filtered through
-    /// [`solitaire_core::solver::try_solve`] until one is provably
+    /// [`solitaire_data::solver::try_solve`] until one is provably
     /// winnable (or the retry cap is hit). Off by default.
     ToggleWinnableDealsOnly,
     /// Toggle the inverse of [`Settings::disable_smart_default_size`].