feat(signal_v2-phase3a): main.py lifespan integrates KIS client + WS

AppContext extended with kis_client + kis_ws. lifespan:
- If KIS_APP_KEY set: create KISClient + KISWebSocket, fetch portfolio,
  subscribe WebSocket H0STASP0 for holdings.
- If unset: WARNING log, signal_v2 still serves /health (no KIS data).
- Shutdown closes kis_ws → kis_client → stock client in order.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

signal_v2/tests/test_main.py

@@ -34,3 +34,20 @@ def test_startup_warns_if_webai_api_key_missing(monkeypatch, caplog):
         with TestClient(main_mod.app) as client:
             client.get("/health")
         assert any("WEBAI_API_KEY" in rec.message for rec in caplog.records)
+
+
+def test_startup_warns_if_kis_app_key_missing(monkeypatch, caplog):
+    """KIS_APP_KEY 미설정 시 startup WARNING (KIS 호출 disabled)."""
+    monkeypatch.setenv("STOCK_API_URL", "https://test.stock.local")
+    monkeypatch.setenv("WEBAI_API_KEY", "test-secret")
+    monkeypatch.delenv("KIS_APP_KEY", raising=False)
+
+    import importlib
+    from signal_v2 import config as cfg
+    importlib.reload(cfg)
+    from signal_v2 import main as main_mod
+    importlib.reload(main_mod)
+    with caplog.at_level(logging.WARNING, logger="signal_v2.main"):
+        with TestClient(main_mod.app) as client:
+            client.get("/health")
+        assert any("KIS_APP_KEY" in rec.message for rec in caplog.records)