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/klondike_adapter.rs

@@ -18,7 +18,16 @@ use klondike::{
 use serde::{Deserialize, Serialize};
 
 use crate::card;
-use crate::game_state::{DrawMode, GameMode};
+use crate::game_state::GameMode;
+
+/// Whether cards are drawn one at a time or three at a time from the stock.
+#[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]
+pub enum DrawMode {
+    /// Draw one card from stock per turn.
+    DrawOne,
+    /// Draw three cards from stock per turn; only the top is playable.
+    DrawThree,
+}
 
 /// Bridges `solitaire_core` game config and scoring to the upstream `klondike` crate.
 ///