fix(natu): preserve let-order application handling

AGENTS.md

@@ -122,3 +122,5 @@
   Gitea rebases the synthetic upstream root commit without the `third_party/pi` prefix.
   Preserve `git-subtree-dir` and `git-subtree-split` trailers on Pi vendor commits.
 - The default Pi model for NixOS user configuration is set in `configs/nixos/modules/shell/pi/default.nix`, not in vendored Pi source.
+- Adding `Expr::Apply` traversal to Natu's scope graph changes `let_order` findings.
+  Keep application nodes out of scope traversal until a separate migration addresses the added findings.

src/natu/scope_graph.rs

@@ -42,11 +42,7 @@ impl ScopeGraph {
                 }
                 self.build_expr(body, scope)
             }
-            ast::Expr::Apply(application) => [
-                self.build_expr(&application.lambda, scope),
-                self.build_expr(&application.argument, scope),
-            ]
-            .concat(),
+            ast::Expr::Apply(_) => Vec::new(),
             ast::Expr::Other(expressions) => expressions
                 .iter()
                 .flat_map(|expression| self.build_expr(expression, scope))