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_data/src/lib.rs

@@ -99,6 +99,12 @@ impl SyncProvider for Box<dyn SyncProvider + Send + Sync> {
     }
 }
 
+pub mod solver;
+pub use solver::{
+    SolveOutcome, SolverConfig, SolverMove, SolverResult, try_solve, try_solve_from_state,
+    try_solve_with_first_move,
+};
+
 pub mod stats;
 pub use stats::{StatsExt, StatsSnapshot};