refactor(simulation): apply rustfmt formatting

Formatting-only changes across server source and test files.
No logic changes.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/perception/observer/tests.rs

@@ -1948,7 +1948,11 @@ fn equidistant_npcs_produce_stable_snapshot_ordering() {
         .map(|e| e.entity_id)
         .collect();
 
-    assert_eq!(npc_ids.len(), 3, "all three equidistant NPCs should be visible");
+    assert_eq!(
+        npc_ids.len(),
+        3,
+        "all three equidistant NPCs should be visible"
+    );
 
     // Entity IDs must be in strictly ascending order (Fix B sort guarantee)
     for i in 1..npc_ids.len() {