feat(bx): add occur_date column on reimburse detail

Store optional expense occurrence date (DATE, nullable) for each
reimburse line item.

Co-authored-by: Cursor <cursoragent@cursor.com>

backend/app/models/bx_models.py

@@ -194,6 +194,7 @@ class BxReimburseDetail(Base):
     expense_id = Column(String(64), nullable=False, comment="费用项目ID")
     expense_name = Column(String(128), nullable=False, comment="费用项目名称")
     amount = Column(DECIMAL(14, 2), nullable=False, comment="报销金额")
+    occur_date = Column(Date, nullable=True, comment="费用发生日期")
     tenant_no = Column(String(64), nullable=False, default="shanxia2.0", comment="租户编号")
     order_num = Column(Integer, nullable=True, comment="排序号(公共)")
     remark = Column(String(512), nullable=True, comment="备注")

backend/scripts/migrate_20260817_bx_reimburse_detail_occur_date.sql

@@ -0,0 +1,6 @@
+-- backend/scripts/migrate_20260817_bx_reimburse_detail_occur_date.sql
+-- 报销明细增加可选发生日期 occur_date
+
+ALTER TABLE `bx_reimburse_detail`
+  ADD COLUMN `occur_date` date DEFAULT NULL COMMENT '费用发生日期'
+  AFTER `amount`;

docs/sql/shanxia2.0.sql

@@ -953,6 +953,7 @@ CREATE TABLE `bx_reimburse_detail` (
   `expense_id` varchar(64) NOT NULL COMMENT '费用项目ID',
   `expense_name` varchar(128) NOT NULL COMMENT '费用项目名称',
   `amount` decimal(14,2) NOT NULL COMMENT '报销金额',
+  `occur_date` date DEFAULT NULL COMMENT '费用发生日期',
   `tenant_no` varchar(64) NOT NULL DEFAULT 'shanxia2.0' COMMENT '租户编号',
   `order_num` int(11) DEFAULT NULL COMMENT '排序号(公共)',
   `remark` varchar(512) DEFAULT NULL COMMENT '备注',