docs: document Tencent quote refresh

tests/test_tencent_quotes.py

@@ -64,3 +64,13 @@ def test_provider_builds_batch_query_and_maps_by_code():
 
     assert "q=sz000001" in calls[0]
     assert quotes["000001"].price == Decimal("10.60")
+
+
+def test_provider_wraps_fetch_errors():
+    def failing_fetch(url: str, timeout: float) -> bytes:
+        raise OSError("bad gateway")
+
+    provider = TencentQuoteProvider(fetcher=failing_fetch)
+
+    with pytest.raises(QuoteFetchError, match="Tencent quote request failed"):
+        provider.fetch_quotes([Instrument(id=1, code="000001", name="平安银行")])