fix(management): 评审修正——config_json注解对齐NOT NULL+补3个约束测试

- EmployeeScoreConfig.config_json 去掉 | None,注解与 DDL(nullable=False)一致
- 删测试死 import datetime as dt
- 补约束测试: metric_daily 复合PK防重/ call_daily PK防重/ config_json NOT NULL
  (JSON 列 Python None 序列化为 'null' 字符串,测 NOT NULL 须 sa.null())
- EmployeeScoreConfig docstring 补 JSON 列整列重赋值注记

Co-Authored-By: Claude Code <noreply@anthropic.com>

yunke-server/app/db/models.py

@@ -1129,7 +1129,8 @@ class EmployeeCallDaily(Base):
 class EmployeeScoreConfig(Base):
     """评分配置版本(v1 §10.4/v2 §3.3)——config_json 存维度/指标/权重/
     方向/阈值/样本门槛;激活前须过权重总和与阈值校验(批次B scoring 实现)。
-    MVP 无可视化编辑器,受控 CLI 种子维护。"""
+    MVP 无可视化编辑器,受控 CLI 种子维护。
+    JSON 列(config_json 等)修改须整列重赋值,原地修改不会提交。"""
 
     __tablename__ = "employee_score_config"
 
@@ -1142,7 +1143,7 @@ class EmployeeScoreConfig(Base):
     )
     effective_from: Mapped[int | None] = mapped_column(Integer, nullable=True)
     effective_to: Mapped[int | None] = mapped_column(Integer, nullable=True)
-    config_json: Mapped[dict[str, Any] | None] = mapped_column(JSON, nullable=False)
+    config_json: Mapped[dict[str, Any]] = mapped_column(JSON, nullable=False)
     created_by: Mapped[str | None] = mapped_column(String(64), nullable=True)
     approved_by: Mapped[str | None] = mapped_column(String(64), nullable=True)
     created_at: Mapped[dt.datetime] = mapped_column(