feat: scene close on hard signals with manual override

tests/test_turn_flow.py

@@ -43,6 +43,13 @@ def client(tmp_path, monkeypatch):
     canned_state_update = json.dumps(
         {"affinity_delta": 0, "trust_delta": 0, "knowledge_facts": []}
     )
+    # T26 scene-close detection runs after the state-update pass. These
+    # tests don't seed an active scene so the classifier is short-circuited
+    # in turns.py — but the canned slot is harmless to leave in place,
+    # and adding it documents the order even when the call doesn't fire.
+    canned_scene_close = json.dumps(
+        {"should_close": False, "reason": "no signal"}
+    )
 
     # Import here so env vars are visible to the dependency lookup.
     from chat.web.kickoff import get_llm_client
@@ -53,6 +60,7 @@ def client(tmp_path, monkeypatch):
             canned_response,
             canned_state_update,
             canned_state_update,
+            canned_scene_close,
         ]
     )
     app.dependency_overrides[get_llm_client] = lambda: mock