feat(crypto-tail): 策略最小价差(无/固定/自动) + 前端默认与文案

- 后端: 最小价差 DB/Entity/DTO、Binance K线 REST+WS、自动价差 IQR 预计算与执行时校验
- 前端: 最小价差(自动-固定-无)，默认自动，label 旁 info 说明，选择自动不展示建议约
- i18n: minSpreadModeTip 说明不写死标的
- 文档: crypto-tail-strategy-min-spread-flow.md
- scripts: Binance K线拉取与 WS 示例

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

scripts/fetch_binance_btc_usdc_klines.py

@@ -0,0 +1,105 @@
+#!/usr/bin/env python3
+"""
+从币安现货 API 获取 BTC/USDC 15 分钟 K 线数据。
+
+API: https://api.binance.com/api/v3/klines
+无需 API Key，公开行情接口。
+
+使用方法:
+  python3 scripts/fetch_binance_btc_usdc_klines.py
+  python3 scripts/fetch_binance_btc_usdc_klines.py --limit 96
+  python3 scripts/fetch_binance_btc_usdc_klines.py --limit 10 --interval 15m
+"""
+import argparse
+import json
+import sys
+import time
+import urllib.error
+import urllib.parse
+import urllib.request
+
+BINANCE_BASE = "https://api.binance.com"
+
+
+def fetch_klines(
+    symbol: str = "BTCUSDC",
+    interval: str = "15m",
+    limit: int = 500,
+    start_time: int | None = None,
+    end_time: int | None = None,
+) -> list[list] | None:
+    """
+    获取 K 线数据。
+    返回每根 K 线: [ openTime, open, high, low, close, volume, closeTime, ... ]
+    """
+    params = {"symbol": symbol, "interval": interval, "limit": limit}
+    if start_time is not None:
+        params["startTime"] = start_time
+    if end_time is not None:
+        params["endTime"] = end_time
+    qs = urllib.parse.urlencode(params)
+    url = f"{BINANCE_BASE}/api/v3/klines?{qs}"
+    req = urllib.request.Request(url, headers={"User-Agent": "PolymarketBot/1.0 (script)"})
+    try:
+        with urllib.request.urlopen(req, timeout=15) as resp:
+            return json.load(resp)
+    except urllib.error.HTTPError as e:
+        body = e.read().decode() if e.fp else ""
+        try:
+            err = json.loads(body)
+        except json.JSONDecodeError:
+            err = {"msg": body}
+        print(f"Request failed: {e.code} - {err}", file=sys.stderr)
+        return None
+    except Exception as e:
+        print(f"Request error: {e}", file=sys.stderr)
+        return None
+
+
+def main():
+    parser = argparse.ArgumentParser(description="Fetch Binance BTC/USDC 15m klines")
+    parser.add_argument("--symbol", default="BTCUSDC", help="Trading pair (default: BTCUSDC)")
+    parser.add_argument("--interval", default="15m", help="Kline interval (default: 15m)")
+    parser.add_argument("--limit", type=int, default=20, help="Number of klines (default: 20, max 1000)")
+    parser.add_argument("--start", type=int, default=None, help="Start time (ms)")
+    parser.add_argument("--end", type=int, default=None, help="End time (ms)")
+    args = parser.parse_args()
+
+    limit = max(1, min(1000, args.limit))
+
+    print("=== Binance BTC/USDC K-line (15m) ===\n")
+    print(f"Symbol: {args.symbol}  Interval: {args.interval}  Limit: {limit}")
+    if args.start:
+        print(f"Start: {args.start} ({time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(args.start // 1000))})")
+    if args.end:
+        print(f"End:   {args.end} ({time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(args.end // 1000))})")
+    print()
+
+    klines = fetch_klines(
+        symbol=args.symbol,
+        interval=args.interval,
+        limit=limit,
+        start_time=args.start,
+        end_time=args.end,
+    )
+
+    if not klines:
+        print("No kline data returned")
+        sys.exit(1)
+
+    print(f"Got {len(klines)} kline(s)\n")
+    print("Columns: openTime, open, high, low, close, volume, closeTime, ...")
+    print("-" * 72)
+    for k in klines:
+        open_ts_ms = k[0]
+        open_ts = open_ts_ms // 1000
+        ts_str = time.strftime("%Y-%m-%d %H:%M:%S", time.localtime(open_ts))
+        o, h, l, c, v = k[1], k[2], k[3], k[4], k[5]
+        print(f"  {ts_str}  O:{o}  H:{h}  L:{l}  C:{c}  V:{v}")
+    print("-" * 72)
+    last = klines[-1]
+    print(f"Latest: open={last[1]}, high={last[2]}, low={last[3]}, close={last[4]}, volume={last[5]}")
+
+
+if __name__ == "__main__":
+    main()