fix(ai): enforce zero-relative clause preservation and anti-omission rules in literary prompt

tests/test_api.py

@@ -1920,7 +1920,8 @@ def test_robust_sentence_split_and_ai_translation(monkeypatch):
     assert "briefcase" in prompt
     assert "портфель, кейс, дипломат" in prompt
     assert "Mr. -> мистер" in prompt
-    assert "НЕ дословным, без топорного калькирования" in prompt
+    assert "БЕЗ ДОСЛОВНОГО КАЛЬКИРОВАНИЯ" in prompt
+    assert "ПОЛНОТА И СВЯЗНОСТЬ" in prompt
 
     # 3. Test API endpoint /api/translate-sentence
     # Authenticate client