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/sync_plugin.rs

@@ -301,9 +301,9 @@ fn push_on_exit(
     exit_events.clear();
 
     let payload = build_payload(&stats.0, &achievements.0, &progress.0);
-    let result = rt
-        .0
-        .block_on(async { tokio::time::timeout(EXIT_PUSH_TIMEOUT, provider.0.push(&payload)).await });
+    let result = rt.0.block_on(async {
+        tokio::time::timeout(EXIT_PUSH_TIMEOUT, provider.0.push(&payload)).await
+    });
     match result {
         Ok(Ok(_)) | Ok(Err(SyncError::UnsupportedPlatform)) => {}
         Ok(Err(e)) => warn!("sync push on exit failed: {e}"),
@@ -667,9 +667,7 @@ mod tests {
         );
 
         // In-memory contract: replays[0].share_url is now Some(url).
-        let live = app
-            .world()
-            .resource::<ReplayHistoryResource>();
+        let live = app.world().resource::<ReplayHistoryResource>();
         assert_eq!(
             live.0.replays.first().and_then(|r| r.share_url.clone()),
             Some(url.clone()),