style(simulation): cargo fmt on the step-canvas batch

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

server/tests/step_canvas_acceptance_gate.rs

@@ -302,18 +302,22 @@ fn step_canvas_cache_round_trip_matches_fresh_derive_every_fixed_rung() {
         let rn = fixture_river_network(&hm);
         let params = fixture_params();
         let fresh_raw = build_step_canvas(
-            seed, "gate-body", &params, &ta, &rn, &[], rung, center, extent, &climate, min_wl_m,
+            seed,
+            "gate-body",
+            &params,
+            &ta,
+            &rn,
+            &[],
+            rung,
+            center,
+            extent,
+            &climate,
+            min_wl_m,
         );
         let fresh_encoded = encode_step_canvas(&fresh_raw);
 
         let mut cache = StepCanvasCache::new(8);
-        let key = (
-            "gate-body".to_string(),
-            rung,
-            center,
-            extent,
-            min_wl_m,
-        );
+        let key = ("gate-body".to_string(), rung, center, extent, min_wl_m);
         assert!(cache.get(&key, 0, body_class).is_none());
         cache.insert(key.clone(), fresh_encoded.clone(), 0);
 
@@ -331,7 +335,16 @@ fn step_canvas_cache_round_trip_matches_fresh_derive_every_fixed_rung() {
         let rn2 = fixture_river_network(&hm2);
         let params2 = fixture_params();
         let recomputed_raw = build_step_canvas(
-            seed, "gate-body", &params2, &ta2, &rn2, &[], rung, center, extent, &climate,
+            seed,
+            "gate-body",
+            &params2,
+            &ta2,
+            &rn2,
+            &[],
+            rung,
+            center,
+            extent,
+            &climate,
             min_wl_m,
         );
         let recomputed_encoded = encode_step_canvas(&recomputed_raw);