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/kpis.py

@@ -11,6 +11,7 @@ from app.deps import get_entity_id
 from app.auth_middleware import require_auth, require_role, filter_kpis_by_role, kpi_visible_dims
 from app.models import StrategicMap, MapObjective, KPIDefinition, KPIValue, KPIAlert, OperationLog, Entity, KPICausality, KPIHierarchy, User
 from app.utils.oplog import log_op
+from app.utils.alert_entity_scope import month_period_clause
 from app.api.kpi_governance import validate_kpi_payload, kpi_issues_message
 from app.utils.threshold_parser import (
     calc_level as _tp_calc_level,
@@ -200,6 +201,7 @@ def get_kpi_score(
         )
         if period:
             val_query = val_query.filter(KPIValue.period == period)
+        val_query = val_query.filter(month_period_clause(KPIValue.period))
         latest_val = val_query.order_by(KPIValue.period.desc()).first()
 
         current_val = latest_val.actual_value if latest_val else None
@@ -291,6 +293,7 @@ def get_kpi_glossary(
         latest_val = db.query(KPIValue).filter(
             KPIValue.kpi_id == k.id,
             KPIValue.actual_value.isnot(None),
+            month_period_clause(KPIValue.period),
         ).order_by(KPIValue.period.desc()).first()
 
         current_value = latest_val.actual_value if latest_val else None
@@ -568,7 +571,9 @@ def list_kpi_values(
         raise HTTPException(404, "KPI不存在")
     if kpi.entity_id != entity_id:
         raise HTTPException(404, "KPI不存在")
-    vals = db.query(KPIValue).filter(KPIValue.kpi_id == kpi_id).order_by(KPIValue.period.desc()).all()
+    vals = db.query(KPIValue).filter(
+        KPIValue.kpi_id == kpi_id, month_period_clause(KPIValue.period)
+    ).order_by(KPIValue.period.desc()).all()
     return {
         "data": [{
             "id": v.id,