fix(fetch-caliber): 取数层排除半年/预测伪期间 + subjects 响应补 entity_id

R3 期间口径（仅 YYYY-MM）延伸到取数层：新增 alert_entity_scope.month_period_clause()（跨库可移植 SQL 等价式），应用到 15 个文件 26 处「按 period 倒序取最新值/最近N期」位点；dashboard 原 MySQL-only REGEXP 正则收口到同单一事实源。

GET /api/cma/subjects 响应增补 entity_id（NULL=全局标准准则科目 / N=账套私有明细），既有 10 字段语义与名称不变。

证据：pending-tasks/_reports/yanxue-20260924-cma-fetch-caliber-fixes-fullstack.md（改前/改后 A/B：F_NET_PROFIT 2026-H2/-55.0 → 2026-08/-10.46）。新增 7 例回归测试；全量 1 failed(预存在) 1473 passed，基线同项。

backend/app/api/data_quality.py

@@ -14,6 +14,7 @@ from app.deps import assert_entity_scope, get_entity_id
 from app.auth_middleware import require_auth, require_role
 from app.models import KPIDefinition, KPIValue, KpiDataQualityLog, OperationLog
 from app.api.kpis import kpi_to_dict
+from app.utils.alert_entity_scope import month_period_clause
 
 logger = logging.getLogger("data-quality")
 
@@ -74,6 +75,7 @@ def run_quality_check(db: Session = Depends(get_db), entity_id: int = Depends(ge
         values = db.query(KPIValue).filter(
             KPIValue.kpi_id == kpi.id,
             KPIValue.actual_value.isnot(None),
+            month_period_clause(KPIValue.period),
         ).order_by(KPIValue.period.desc()).limit(12).all()
 
         # 1. 检查数据缺失
@@ -365,6 +367,7 @@ def quality_stats(db: Session = Depends(get_db), entity_id: int = Depends(get_en
         latest_val = db.query(KPIValue).filter(
             KPIValue.kpi_id == kpi.id,
             KPIValue.actual_value.isnot(None),
+            month_period_clause(KPIValue.period),
         ).order_by(KPIValue.period.desc()).first()
         if latest_val and latest_val.calculated_at:
             if latest_val.calculated_at < stale_threshold: