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_web/src/lib.rs

@@ -41,8 +41,7 @@ pub fn start() {
                         // texture-dimension limit is now taken from the adapter (see
                         // the RenderPlugin below), so this is purely a quality/perf
                         // choice, no longer a crash-avoidance hack.
-                        resolution: WindowResolution::default()
-                            .with_scale_factor_override(1.0),
+                        resolution: WindowResolution::default().with_scale_factor_override(1.0),
                         ..default()
                     }),
                     ..default()