style: cargo fmt under rustfmt 1.9 and gate formatting in CI

The repo was formatted under an older stable; rustfmt 1.9 (Rust 1.95)
wraps signatures and call sites differently, so every touched file was
picking up unrelated formatting hunks. One mechanical pass, and a
'cargo fmt --check' step in the test workflow (same pinned 1.95.0
toolchain) so drift can't accumulate again.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

solitaire_engine/src/home_plugin.rs

@@ -432,7 +432,9 @@ fn build_home_context<'a>(
         zen_best: stats.map_or(0, |s| s.0.zen_best_score),
         challenge_best: stats.map_or(0, |s| s.0.challenge_best_score),
         daily_today,
-        draw_mode: settings.map(|s| s.0.draw_mode).unwrap_or(DrawStockConfig::DrawOne),
+        draw_mode: settings
+            .map(|s| s.0.draw_mode)
+            .unwrap_or(DrawStockConfig::DrawOne),
         font_res,
         difficulty_expanded,
         last_difficulty: settings.and_then(|s| s.0.last_difficulty),