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/resources.rs

@@ -6,8 +6,8 @@ use std::sync::Arc;
 use bevy::math::Vec2;
 use bevy::prelude::Resource;
 use chrono::{DateTime, Utc};
-use solitaire_core::KlondikePile;
 use solitaire_core::Card;
+use solitaire_core::KlondikePile;
 use solitaire_core::game_state::GameState;
 
 /// Wraps the currently active `GameState`. Single source of truth for the in-progress game.