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/content/spawn.rs

@@ -197,9 +197,10 @@ fn spawn_npc(world: &mut World, profile: &types::NpcProfile, result: &mut SpawnR
 
     // Register in EntityRegistry for StableId mapping
     let stable_id = world.resource_mut::<EntityRegistry>().register(entity);
-    world
-        .entity_mut(entity)
-        .insert((StableEntityId(stable_id), ContentSlug(profile.canonical_id.clone())));
+    world.entity_mut(entity).insert((
+        StableEntityId(stable_id),
+        ContentSlug(profile.canonical_id.clone()),
+    ));
 
     result
         .npc_ids