Polish Novya UI with brand colors, first-load skeletons, and session transition overlay.

Keep chat pinned to the latest message while AI thinks or streams, and align buttons/inputs with the logo teal/blue focus treatment.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/tests/e2e-qa.test.ts

@@ -224,7 +224,8 @@ describe('full E2E learning journey QA', () => {
     const beforeFinal = await requestJson(app, '/journey', { headers: headers(token, ownerIp) });
     assert.equal(
       (beforeFinal.body.data?.permissions as { canTakePostTest: boolean }).canTakePostTest,
-      false,
+      true,
+      'post-test should unlock once the learner reaches session 11',
     );
 
     await completeSession(token, ownerIp, PROGRAM_SESSION_COUNT, owner.user.id);