refactor: worker_id → user_id 전체 마이그레이션 (Phase 1-4)

sso_users.user_id를 단일 식별자로 통합. JWT에서 worker_id 제거,
department_id/is_production 추가. 백엔드 15개 모델, 11개 컨트롤러,
4개 서비스, 7개 라우트, 프론트엔드 32+ JS/11+ HTML 변환.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

system1-factory/api/models/userModel.js

@@ -7,7 +7,7 @@ const findByUsername = async (username) => {
         const [rows] = await db.query(
             `SELECT u.user_id, u.username, u.password, u.name, u.email,
                     u.role_id, r.name as role_name,
-                    u._access_level_old as access_level, u.worker_id, u.is_active,
+                    u._access_level_old as access_level, u.is_active,
                     u.last_login_at, u.password_changed_at, u.failed_login_attempts,
                     u.locked_until, u.created_at, u.updated_at
              FROM users u