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/card_plugin/stock.rs

@@ -2,7 +2,6 @@
 
 use super::*;
 
-
 use bevy::color::Color;
 use solitaire_core::KlondikePile;
 use solitaire_core::game_state::GameState;
@@ -12,10 +11,7 @@ use crate::font_plugin::FontResource;
 use crate::layout::{Layout, LayoutResource};
 use crate::resources::GameStateResource;
 use crate::table_plugin::{PILE_MARKER_DEFAULT_COLOUR, PileMarker};
-use crate::ui_theme::{
-    STOCK_BADGE_BG, STOCK_BADGE_FG, TEXT_PRIMARY,
-    TYPE_BODY, Z_STOCK_BADGE,
-};
+use crate::ui_theme::{STOCK_BADGE_BG, STOCK_BADGE_FG, TEXT_PRIMARY, TYPE_BODY, Z_STOCK_BADGE};
 
 /// Sprite colour applied to the stock `PileMarker` when the stock pile is empty,
 /// to signal to the player that there are no more cards to draw. Pure white
@@ -288,4 +284,3 @@ pub(super) fn update_stock_count_badge(
         }
     }
 }
-