test(smoke): fix remaining 6 failures (#8)

- 02 search: target the visible .hero-search instance; the old .first()
  selector matched the hidden header search-overlay (instance 1).
- 01 calculator: it auto-computes from the peptide preset; select the peptide
  and assert #prc-results, scoped to .prc-calculator (the old broad
  button[type=submit] selector clicked the PSA search button).
- 03 admin: 'const nav' had been swallowed into a comment (ReferenceError).
- 04 rest-api: PSA /search returns {results:[]} with no 'status' key; drop it.

Auth fixed separately via a dedicated staging CI admin (ci-smoke) + corrected
STAGING_WP_ADMIN_* secrets; the global.setup failure was cascading into these.

Agent-Session: cto smoke-green

Co-authored-by: peptiderepo <peptiderepo@users.noreply.github.com>

tests/04-rest-api.spec.ts

@@ -38,7 +38,6 @@ test.describe('REST API — Peptide Search AI', () => {
     expect([200, 404]).toContain(res.status());
     if (res.status() === 200) {
       const body = await res.json();
-      expect(body).toHaveProperty('status');
       expect(body).toHaveProperty('results');
     }
   });