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/play_by_seed_plugin.rs

@@ -23,7 +23,7 @@
 use bevy::input::ButtonInput;
 use bevy::prelude::*;
 use bevy::tasks::{AsyncComputeTaskPool, Task, futures_lite::future};
-use solitaire_core::DrawMode;
+use solitaire_core::DrawStockConfig;
 use solitaire_core::game_state::GameState;
 use solitaire_core::{DEFAULT_SOLVE_MOVES_BUDGET, DEFAULT_SOLVE_STATES_BUDGET, SolveOutcome};
 
@@ -340,7 +340,7 @@ fn tick_debounce_and_spawn_solver_task(
 
     let draw_mode = settings
         .as_ref()
-        .map_or(DrawMode::DrawOne, |s| s.0.draw_mode);
+        .map_or(DrawStockConfig::DrawOne, |s| s.0.draw_mode);
     let task = AsyncComputeTaskPool::get().spawn(async move {
         GameState::solve_fresh_deal(
             seed,