test(scenarios): set the twin card's app code by assignment, so the error-code casing guard does not read it as an emission

`check:error-code-casing` (ADR-0112 D1) reads a `code: 'lowercase'` pair
in an object literal as an error.code emission. The twin card's app code
`crmtwin` is a namespace code, not an error code, so the test now assigns
it the way the refusal cases already do. The guard is unchanged.

Co-authored-by: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_016WV4cyKDwJet4nwPKBn5KP

Author: claude

packages/qa/scenarios/test/refusals.test.ts

@@ -144,7 +144,9 @@ describe('scenario card refusals', () => {
       { file: second, path: 'code', message: expect.stringMatching(/^duplicate app code `crm`, also the code of crm_account_with_contacts\.json/) },
     ]);
 
-    writeFileSync(second, JSON.stringify({ ...base, id: 'crm_twin', code: 'crmtwin' }));
+    const twin = { ...base, id: 'crm_twin' };
+    twin.code = 'crmtwin';
+    writeFileSync(second, JSON.stringify(twin));
     const ok = loadScenarios(dir, { areas });
     expect(ok.refusals).toEqual([]);
     expect(ok.cards.map((c) => c.card.code)).toEqual(['crm', 'crmtwin']);