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/feedback_anim_plugin.rs

@@ -850,7 +850,7 @@ mod tests {
     fn shake_anim_skipped_under_reduce_motion() {
         use bevy::ecs::message::Messages;
         use solitaire_core::Tableau;
-        use solitaire_core::game_state::{DrawMode, GameState};
+        use solitaire_core::{DrawMode, game_state::GameState};
         use solitaire_data::Settings;
 
         let mut app = App::new();
@@ -904,7 +904,7 @@ mod tests {
     #[test]
     fn foundation_flourish_skipped_under_reduce_motion() {
         use bevy::ecs::message::Messages;
-        use solitaire_core::game_state::{DrawMode, GameState};
+        use solitaire_core::{DrawMode, game_state::GameState};
         use solitaire_data::Settings;
 
         let mut app = App::new();