feat(tkuser): Sprint 001 Section A — 연차/휴가 백엔드 전환 (DB + API)

workers/vacation_balance_details → sso_users/sp_vacation_balances 기반 전환.
부서장 설정, 승인권한 CRUD, vacation_settings 테이블, 장기근속 자동부여,
startup migration 추가.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

user-management/api/models/departmentModel.js

@@ -1,7 +1,7 @@
 /**
  * Department Model
  *
- * departments 테이블 CRUD (MariaDB)
+ * departments 테이블 CRUD + 승인권한 관리 (MariaDB)
  */
 
 const { getPool } = require('./userModel');
@@ -9,8 +9,9 @@ const { getPool } = require('./userModel');
 async function getAll() {
   const db = getPool();
   const [rows] = await db.query(
-    `SELECT d.*
+    `SELECT d.*, su.name AS leader_name
      FROM departments d
+     LEFT JOIN sso_users su ON d.leader_user_id = su.user_id
      ORDER BY d.display_order ASC, d.department_id ASC`
   );
   return rows;
@@ -19,8 +20,9 @@ async function getAll() {
 async function getById(id) {
   const db = getPool();
   const [rows] = await db.query(
-    `SELECT d.*
+    `SELECT d.*, su.name AS leader_name
      FROM departments d
+     LEFT JOIN sso_users su ON d.leader_user_id = su.user_id
      WHERE d.department_id = ?`,
     [id]
   );
@@ -45,6 +47,7 @@ async function update(id, data) {
   if (data.department_name !== undefined) { fields.push('department_name = ?'); values.push(data.department_name); }
   if (data.description !== undefined) { fields.push('description = ?'); values.push(data.description || null); }
   if (data.display_order !== undefined) { fields.push('display_order = ?'); values.push(data.display_order); }
+  if (data.leader_user_id !== undefined) { fields.push('leader_user_id = ?'); values.push(data.leader_user_id || null); }
 
   if (fields.length === 0) return getById(id);
 
@@ -61,6 +64,8 @@ async function remove(id) {
   const conn = await db.getConnection();
   try {
     await conn.beginTransaction();
+    // CASCADE가 있지만 방어적으로 명시 삭제
+    await conn.query('DELETE FROM dept_approval_authority WHERE department_id = ?', [id]);
     await conn.query('UPDATE users SET department_id = NULL WHERE department_id = ?', [id]);
     await conn.query('DELETE FROM departments WHERE department_id = ?', [id]);
     await conn.commit();
@@ -72,4 +77,57 @@ async function remove(id) {
   }
 }
 
-module.exports = { getAll, getById, create, update, remove };
+/* ===== 승인권한 (Approval Authority) ===== */
+
+async function getApprovalAuthorities(departmentId) {
+  const db = getPool();
+  const [rows] = await db.query(
+    `SELECT aa.*, su.name AS approver_name
+     FROM dept_approval_authority aa
+     JOIN sso_users su ON aa.approver_user_id = su.user_id
+     WHERE aa.department_id = ? AND aa.is_active = TRUE
+     ORDER BY aa.approval_type ASC, aa.priority ASC`,
+    [departmentId]
+  );
+  return rows;
+}
+
+async function createApprovalAuthority({ department_id, approval_type, approver_user_id, priority }) {
+  const db = getPool();
+  const [result] = await db.query(
+    `INSERT INTO dept_approval_authority (department_id, approval_type, approver_user_id, priority)
+     VALUES (?, ?, ?, ?)`,
+    [department_id, approval_type, approver_user_id, priority || 1]
+  );
+  const [rows] = await db.query(
+    `SELECT aa.*, su.name AS approver_name
+     FROM dept_approval_authority aa
+     JOIN sso_users su ON aa.approver_user_id = su.user_id
+     WHERE aa.id = ?`,
+    [result.insertId]
+  );
+  return rows[0] || null;
+}
+
+async function deleteApprovalAuthority(id) {
+  const db = getPool();
+  await db.query('DELETE FROM dept_approval_authority WHERE id = ?', [id]);
+}
+
+async function getApproversByType(departmentId, approvalType) {
+  const db = getPool();
+  const [rows] = await db.query(
+    `SELECT aa.*, su.name AS approver_name
+     FROM dept_approval_authority aa
+     JOIN sso_users su ON aa.approver_user_id = su.user_id
+     WHERE aa.department_id = ? AND aa.approval_type = ? AND aa.is_active = TRUE
+     ORDER BY aa.priority ASC`,
+    [departmentId, approvalType]
+  );
+  return rows;
+}
+
+module.exports = {
+  getAll, getById, create, update, remove,
+  getApprovalAuthorities, createApprovalAuthority, deleteApprovalAuthority, getApproversByType
+};