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/sync_plugin.rs

@@ -604,7 +604,7 @@ mod tests {
     /// would silently drop the link.
     #[test]
     fn upload_result_writes_share_url_into_replay_and_persists() {
-        use solitaire_core::{DrawMode, game_state::GameMode};
+        use solitaire_core::{DrawStockConfig, game_state::GameMode};
         use solitaire_data::{
             Replay, ReplayHistory, load_replay_history_from, save_replay_history_to,
         };
@@ -617,7 +617,7 @@ mod tests {
         // share_url — the upload-poll path must populate it.
         let initial = Replay::new(
             42,
-            DrawMode::DrawOne,
+            DrawStockConfig::DrawOne,
             GameMode::Classic,
             60,
             500,