refactor: replace local DrawMode with upstream klondike::DrawStockConfig (#82)

DrawMode was a 1:1 mirror of klondike::DrawStockConfig (DrawOne/DrawThree).
Delete it and use the upstream type everywhere; re-export DrawStockConfig from
solitaire_core. config_for assigns draw_stock directly and draw_mode() returns
session.config().inner.draw_stock.

Serde is unchanged — DrawStockConfig serialises to the same "DrawOne"/"DrawThree"
named variants, so persisted game_state.json / replay JSON stay byte-compatible
(no migration). Field/method/variable names containing draw_mode are unchanged.

35 files, mechanical type swap across all crates. Implemented via a multi-agent
workflow (core → per-crate consumers → verify). cargo test --workspace and
clippy --workspace --all-targets -- -D warnings green.

Closes #82

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

solitaire_engine/src/auto_complete_plugin.rs

@@ -169,7 +169,7 @@ mod tests {
     use crate::table_plugin::TablePlugin;
     use solitaire_core::{Foundation, KlondikePile, Tableau};
     use solitaire_core::card::{Deck, Rank, Suit};
-    use solitaire_core::{DrawMode, game_state::GameState};
+    use solitaire_core::{DrawStockConfig, game_state::GameState};
 
     fn headless_app() -> App {
         let mut app = App::new();
@@ -183,7 +183,7 @@ mod tests {
     }
 
     fn seeded_state_with_auto_move() -> (GameState, (KlondikePile, KlondikePile)) {
-        let mut g = GameState::new(1, DrawMode::DrawOne);
+        let mut g = GameState::new(1, DrawStockConfig::DrawOne);
         g.set_test_stock_cards(Vec::new());
         g.set_test_waste_cards(Vec::new());
         for foundation in [
@@ -227,7 +227,7 @@ mod tests {
     #[test]
     fn detect_activates_when_auto_completable() {
         let mut app = headless_app();
-        let mut g = GameState::new(42, DrawMode::DrawOne);
+        let mut g = GameState::new(42, DrawStockConfig::DrawOne);
         g.set_test_auto_completable(true);
         app.world_mut().resource_mut::<GameStateResource>().0 = g;
         app.world_mut().write_message(StateChangedEvent);