fix: retry transient Tencent quote failures

tests/test_tencent_quotes.py

@@ -74,3 +74,25 @@ def test_provider_wraps_fetch_errors():
 
     with pytest.raises(QuoteFetchError, match="Tencent quote request failed"):
         provider.fetch_quotes([Instrument(id=1, code="000001", name="平安银行")])
+
+
+def test_provider_retries_once_after_transient_fetch_error():
+    raw = (
+        'v_sz000001="51~平安银行~000001~10.60~10.47~10.44~0~0~0~'
+        '0~0~0~0~0~0~0~0~0~0~0~0~0~0~0~0~0~0~0~0~~20260708161430~0.13~1.24~10.63~10.34";'
+    ).encode("gbk")
+    calls = 0
+
+    def flaky_fetch(url: str, timeout: float) -> bytes:
+        nonlocal calls
+        calls += 1
+        if calls == 1:
+            raise OSError("bad gateway")
+        return raw
+
+    provider = TencentQuoteProvider(fetcher=flaky_fetch, retries=1)
+
+    quotes = provider.fetch_quotes([Instrument(id=1, code="000001", name="平安银行")])
+
+    assert calls == 2
+    assert quotes["000001"].price == Decimal("10.60")