refactor(business): 编辑出参取校验返回值省重查，submit_change 批量预载

- update_receipt 取 _ensure_shipment_of_business 返回值组装出参
  （shipment_id 已赋为 payload 新值，与 get_with_refs 重查同源），
  省一次三表 join；update_shipment 同理取锁定行的 business_no
- 删 business_repository.count_items（无任何调用的死代码，删除保护
  实际走 has_docs）
- submit_change 校验段定义与岗位各一条 IN 批量预载（逐条查询在批次
  扩大时是写侧 N+1）；岗位字典键 casefold 归一保持与单条版 ci 校对
  等价的命中语义；旧值留痕保持逐条（窗口函数优化留待 M3 一并设计）

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

backend/app/repositories/business_repository.py

@@ -197,18 +197,6 @@ def replace_items(session: Session, business_id: int, rows: list[BusinessItem])
     session.flush()
 
 
-def count_items(session: Session, business_ids: list[int]) -> dict[int, int]:
-    """业务明细行数（删除保护备用）。"""
-    if not business_ids:
-        return {}
-    rows = session.execute(
-        select(BusinessItem.business_id, func.count())
-        .where(BusinessItem.business_id.in_(business_ids))
-        .group_by(BusinessItem.business_id)
-    ).all()
-    return dict(rows)
-
-
 def add_status_log(session: Session, log: BusinessStatusLog) -> None:
     """追加状态留痕（不 commit）。"""
     session.add(log)

backend/app/repositories/business_role_repository.py

@@ -25,6 +25,20 @@ def get_by_code(session: Session, role_code: str) -> BusinessRole | None:
     return session.execute(stmt).scalar_one_or_none()
 
 
+def list_by_codes(session: Session, role_codes: list[str]) -> dict[str, BusinessRole]:
+    """按编码批量取岗位（参数批次校验段用，消除逐条 N+1）。
+
+    返回 {编码: 岗位}。MySQL ci 校对下编码大小写变形也能命中，
+    键取库里的规范 role_code，调用方据此把维度值归一为规范值。
+    """
+    if not role_codes:
+        return {}
+    rows = session.execute(
+        select(BusinessRole).where(BusinessRole.role_code.in_(role_codes))
+    ).scalars()
+    return {role.role_code: role for role in rows}
+
+
 def list_roles(
     session: Session,
     *,

backend/app/repositories/param_repository.py

@@ -81,6 +81,21 @@ def get_definition_by_code(session: Session, param_code: str) -> ParamDefinition
     return session.execute(stmt).scalar_one_or_none()
 
 
+def list_definitions_by_codes(
+    session: Session, param_codes: list[str]
+) -> dict[str, ParamDefinition]:
+    """按编码批量取参数定义（提交批次的校验段用，消除逐条 N+1）。
+
+    返回 {编码: 定义}；未定义的编码不在结果中，由调用方判缺失。
+    """
+    if not param_codes:
+        return {}
+    rows = session.execute(
+        select(ParamDefinition).where(ParamDefinition.param_code.in_(param_codes))
+    ).scalars()
+    return {definition.param_code: definition for definition in rows}
+
+
 def list_history(
     session: Session,
     param_id: int,