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>

hub_ohlcv_lib.py

@@ -139,6 +139,26 @@ def price_tick_from_market(exchange, exchange_symbol: str) -> Optional[float]:
     return None
 
 
+def normalize_price_tick(tick: Optional[float]) -> Optional[float]:
+    """将 tick 对齐为 10^-n，避免浮点噪声导致前端 lightweight-charts unexpected base。"""
+    if tick is None:
+        return None
+    try:
+        t = float(tick)
+    except (TypeError, ValueError):
+        return None
+    if t <= 0:
+        return None
+    if t >= 1:
+        return t
+    try:
+        exp = int(round(-math.log10(t)))
+    except (ValueError, OverflowError):
+        return None
+    exp = max(0, min(12, exp))
+    return 10 ** (-exp)
+
+
 def _decimals_from_tick(tick: float) -> int:
     if tick >= 1:
         return 0
@@ -413,7 +433,7 @@ def fetch_ohlcv_for_hub(
         if not merged:
             return {"ok": False, "msg": "交易所未返回 K 线"}
 
-        tick = price_tick_from_market(exchange, ex_sym)
+        tick = normalize_price_tick(price_tick_from_market(exchange, ex_sym))
 
         return {
             "ok": True,