feat: 员工信息管理功能完善

- 将员工表org_no字段迁移至dept_id，关联系统部门表
- 更新员工信息相关DTO、VO和Controller，使用deptId替代orgNo
- 添加员工信息管理OpenSpec规范文档(proposal/design/spec/tasks)
- 更新API文档，反映部门关联变更
- 添加数据库迁移脚本employee_org_no_to_dept_id.sql
- 新增员工信息分页接口测试脚本(PowerShell/Python)
- 更新CLAUDE.md，添加MCP数据库工具使用说明

Co-Authored-By: Claude (glm-4.7) <noreply@anthropic.com>

sql/migration/employee_org_no_to_dept_id.sql

@@ -0,0 +1,68 @@
+-- ================================
+-- 纪检初核系统 - 员工表字段迁移脚本
+-- 功能: 将 org_no 字段改为 dept_id
+-- 创建日期: 2026-01-28
+-- ================================
+
+-- 备份说明：执行前请先备份数据库
+
+USE `discipline-prelim-check`;
+
+-- ----------------------------
+-- 步骤1: 删除旧索引（如果存在）
+-- ----------------------------
+-- 使用存储过程检查并删除索引
+DROP PROCEDURE IF EXISTS drop_index_if_exists;
+DELIMITER //
+CREATE PROCEDURE drop_index_if_exists()
+BEGIN
+    DECLARE index_count INT;
+    SELECT COUNT(*) INTO index_count
+    FROM INFORMATION_SCHEMA.STATISTICS
+    WHERE TABLE_SCHEMA = 'discipline-prelim-check'
+      AND TABLE_NAME = 'dpc_employee'
+      AND INDEX_NAME = 'idx_org_no';
+
+    IF index_count > 0 THEN
+        ALTER TABLE `dpc_employee` DROP INDEX `idx_org_no`;
+    END IF;
+END //
+DELIMITER ;
+
+CALL drop_index_if_exists();
+DROP PROCEDURE IF EXISTS drop_index_if_exists;
+
+-- ----------------------------
+-- 步骤2: 修改字段名和类型
+-- ----------------------------
+ALTER TABLE `dpc_employee`
+  CHANGE COLUMN `org_no` `dept_id` BIGINT DEFAULT NULL COMMENT '所属部门ID';
+
+-- ----------------------------
+-- 步骤3: 创建新索引
+-- ----------------------------
+CREATE INDEX `idx_dept_id` ON `dpc_employee` (`dept_id`);
+
+-- ----------------------------
+-- 验证脚本
+-- ----------------------------
+-- 检查字段是否修改成功
+SELECT
+  COLUMN_NAME,
+  DATA_TYPE,
+  COLUMN_TYPE,
+  IS_NULLABLE,
+  COLUMN_COMMENT
+FROM INFORMATION_SCHEMA.COLUMNS
+WHERE TABLE_SCHEMA = 'discipline-prelim-check'
+  AND TABLE_NAME = 'dpc_employee'
+  AND COLUMN_NAME = 'dept_id';
+
+-- 检查索引是否创建成功
+SELECT
+  INDEX_NAME,
+  COLUMN_NAME
+FROM INFORMATION_SCHEMA.STATISTICS
+WHERE TABLE_SCHEMA = 'discipline-prelim-check'
+  AND TABLE_NAME = 'dpc_employee'
+  AND INDEX_NAME = 'idx_dept_id';