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/hud_plugin/fx.rs

@@ -3,8 +3,6 @@
 
 use super::*;
 
-
-
 /// Auto-fade state for the action button bar. The bar fades out when
 /// the cursor is in the play area (below the HUD band) and back in when
 /// the cursor approaches the top of the window — same UX as a video
@@ -49,7 +47,11 @@ const ACTION_FADE_RATE_PER_SEC: f32 = 6.0;
 /// `target` at a fixed rate so the visual transition is smooth across
 /// variable framerates.
 #[cfg(not(target_os = "android"))]
-pub(super) fn update_action_fade(windows: Query<&Window>, time: Res<Time>, mut fade: ResMut<HudActionFade>) {
+pub(super) fn update_action_fade(
+    windows: Query<&Window>,
+    time: Res<Time>,
+    mut fade: ResMut<HudActionFade>,
+) {
     let Ok(window) = windows.single() else {
         return;
     };
@@ -427,4 +429,3 @@ pub(super) fn lerp_text_color(from: Color, to: Color, t: f32) -> Color {
         from.alpha + (to.alpha - from.alpha) * t,
     )
 }
-