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/replay_playback.rs

@@ -556,7 +556,7 @@ mod tests {
     use bevy::time::TimeUpdateStrategy;
     use chrono::NaiveDate;
     use solitaire_core::{KlondikePile, Tableau};
-    use solitaire_core::{DrawMode, game_state::GameMode};
+    use solitaire_core::{DrawStockConfig, game_state::GameMode};
     use solitaire_core::klondike_adapter::{SavedKlondikePile, SavedTableau};
     use std::time::Duration;
 
@@ -598,7 +598,7 @@ mod tests {
     fn sample_replay_three_moves() -> Replay {
         Replay::new(
             12345,
-            DrawMode::DrawOne,
+            DrawStockConfig::DrawOne,
             GameMode::Classic,
             60,
             500,
@@ -771,7 +771,7 @@ mod tests {
         let mut app = headless_app();
         let one_move = Replay::new(
             42,
-            DrawMode::DrawOne,
+            DrawStockConfig::DrawOne,
             GameMode::Classic,
             10,
             100,
@@ -880,7 +880,7 @@ mod tests {
         fn ten_draws_replay() -> Replay {
             Replay::new(
                 7,
-                DrawMode::DrawOne,
+                DrawStockConfig::DrawOne,
                 GameMode::Classic,
                 10,
                 100,