test(context-bill): a skill-less tree prints no estimate line under --exact

Co-authored-by: capy-ai[bot] <230910855+capy-ai[bot]@users.noreply.github.com>

test/context-bill.test.ts

@@ -975,6 +975,7 @@ describe("--exact (opt-in measurement; offline here via an injected fetch)", ()
     expect(code).toBe(2);
     expect(out.text()).toContain("No SKILL.md files found");
     expect(out.text()).not.toContain("--exact: sending");
+    expect(out.text()).not.toContain("no markdown skill file");
     expect(calls.length).toBe(0);
     expect(receipts).toEqual([]);
   });