test(api): keep test_endpoints hermetic after /dm/narrate wiring

/dm/narrate now makes a real Ollama call (Task 7). The role-endpoint
loop tests in test_endpoints.py had no mock, so every default pytest
run was silently hitting a live Ollama instance on localhost:11434 —
breaking the hermetic-suite constraint. Add an autouse fixture that
stubs narrate.ollama_client.chat and narrate.call_log.record so all
five endpoints stay hermetic; assertions (200 on valid, 422 on
invalid) are unchanged.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

api/tests/test_endpoints.py

@@ -1,8 +1,10 @@
 import json
 from pathlib import Path
 
+import pytest
 from fastapi.testclient import TestClient
 
+import app.narrate as narrate
 from app.main import app
 
 client = TestClient(app)
@@ -14,6 +16,15 @@ ROLE_ENDPOINTS = [
 ]
 
 
+@pytest.fixture(autouse=True)
+def _stub_narrate_model_call(monkeypatch):
+    # /dm/narrate is wired to a real Ollama call (Task 7). These tests exercise
+    # canon-log validation across ALL role endpoints, not model behavior, so
+    # stub the model boundary — keeps the default suite hermetic (no network).
+    monkeypatch.setattr(narrate.ollama_client, "chat", lambda *a, **k: "stubbed prose")
+    monkeypatch.setattr(narrate.call_log, "record", lambda **kw: None)
+
+
 def test_health_ok():
     assert client.get("/health").json() == {"status": "ok"}