feat(screener): 新建策略模板统一 basic_filter 默认值

- 普通与矩阵两个模板统一为: 价格 5~200、流通市值 30~1500 亿 (float_cap)、
  换手率下限 1%、排除 ST、次新 30 天、板块默认不含北交所
- 成交额与总市值下限显式置 None: 引擎合并规则下省略键会继承
  DEFAULT_BASIC_FILTER (成交额 0.2 亿 / 总市值 10 亿), 显式 None 才表达"不设"
- 矩阵模板原无 basic_filter (落库后走引擎兜底), 一并补齐消除两模板不一致

验证: pnpm build 通过; 字段语义核对 (_basic_filter_expr 对 None 跳过,
float_cap=close*float_shares, turnover_rate 为百分数口径, boards 白名单制)。

frontend/src/components/screener/StrategyBuilderDialog.tsx

@@ -94,9 +94,13 @@ META = {
     "asset_types": ["stock"],
     "timeframes": ["1d"],
     "basic_filter": {
-        "price_min": 3, "price_max": 200,
-        "market_cap_min": 10e8, "amount_min": 0.5e8,
+        "price_min": 5, "price_max": 200,
+        "market_cap_min": None,
+        "float_cap_min": 30e8, "float_cap_max": 1500e8,
+        "amount_min": None,
+        "turnover_min": 1,
         "exclude_st": True, "exclude_new_days": 30,
+        "boards": ["沪主板", "深主板", "创业板", "科创板"],
     },
     "params": [],
     "scoring": {
@@ -137,6 +141,15 @@ META = {
     "tags": ["自定义", "矩阵"],
     "asset_types": ["stock"],
     "timeframes": ["1d"],
+    "basic_filter": {
+        "price_min": 5, "price_max": 200,
+        "market_cap_min": None,
+        "float_cap_min": 30e8, "float_cap_max": 1500e8,
+        "amount_min": None,
+        "turnover_min": 1,
+        "exclude_st": True, "exclude_new_days": 30,
+        "boards": ["沪主板", "深主板", "创业板", "科创板"],
+    },
     "params": [],
     "scoring": {},
     "order_by": "score",