fix(hub): 修复币安行情区 unexpected base 价格精度

normalize_price_tick 对齐 tick 为 10^-n；chart.js 使用整数 base 并在 applyOptions 失败时回退安全 priceFormat。

Co-authored-by: Cursor <cursoragent@cursor.com>

tests/test_hub_ohlcv_lib.py

@@ -7,6 +7,7 @@ from hub_ohlcv_lib import (
     aggregate_ohlcv_bars,
     bars_spacing_matches_timeframe,
     fetch_ohlcv_for_hub,
+    normalize_price_tick,
 )
 
 
@@ -30,6 +31,11 @@ class _FakeExchange:
 
 
 class TestHubOhlcvLib(unittest.TestCase):
+    def test_normalize_price_tick_snaps_powers_of_ten(self):
+        self.assertAlmostEqual(normalize_price_tick(0.00001), 0.00001)
+        self.assertAlmostEqual(normalize_price_tick(0.001), 0.001)
+        self.assertIsNone(normalize_price_tick(0))
+
     def test_price_tick_from_decimal_precision(self):
         class _Ex:
             markets = {"BTC/USDT:USDT": {"precision": {"price": 2}, "info": {}, "limits": {}}}