fix(reply): stop weak models parroting persona example facts

A 4b model replied to "하이" with "테니스 연습을 Trenches Gym에서..." — it copied
the literal "box at Trenches Gym" few-shot example embedded in the persona
prompt and mangled boxing into tennis, presenting a prompt example as if it
were a real user fact. Remove the copyable proper-noun example and add an
explicit guard: use ONLY names/places/activities that literally appear in the
memory section, never borrow them from the instructions or example wording.

tests/test_system_prompt.py

@@ -60,6 +60,16 @@ class TestBuildSystemPrompt:
         assert "SINGLE sentence" in prompt
         assert "never add it as " in prompt
 
+    def test_persona_has_no_copyable_proper_noun_examples(self):
+        # A weak model parroted the literal "Trenches Gym" example from the
+        # persona as if it were a real user fact (boxing mangled to tennis).
+        # The persona must not embed copyable personal proper nouns, and must
+        # tell the model to use ONLY facts that literally appear in the memory
+        # section — never borrow names/places from the instructions themselves.
+        prompt = build_system_prompt("Jarvis")
+        assert "Trenches" not in prompt
+        assert "never borrow any name, place, or activity from these instructions" in prompt
+
 
 class TestOutputLanguageDirective:
     """A deployment may lock replies to a single language via OUTPUT_LANGUAGE.