docs: update API documentation tag name from 'items' to 'item'

src/modes/server/api/mod.rs

@@ -31,7 +31,7 @@ use utoipa_swagger_ui::SwaggerUi;
     ),
     tags(
         (name = "status", description = "Status API endpoints"),
-        (name = "items", description = "Item management API endpoints")
+        (name = "item", description = "Item management API endpoints")
     )
 )]
 struct ApiDoc;