chore: 后端首次基线提交

运行必须源码：app/(controller/model/service/middleware/lib/utils/validate/router)、config/、database/(migrations/seeders/sql)、启动脚本、app/public/templates 模板。
已忽略运行非必须：node_modules/、logs/、run/、app/public 运行时上传数据、.env*、构建/缓存产物。

database/seeders/001-seed-competition-info.js

@@ -0,0 +1,21 @@
+'use strict';
+
+module.exports = {
+  up: async (queryInterface, Sequelize) => {
+    const now = new Date();
+    await queryInterface.bulkInsert('competition_info', [
+      {
+        competition_name: '金砖国家职业技能大赛-卫星导航技术应用赛项',
+        competition_code: 'BRICS2026-ST-027',
+        created_at: now,
+        updated_at: now,
+      },
+    ], {});
+  },
+
+  down: async (queryInterface, Sequelize) => {
+    await queryInterface.bulkDelete('competition_info', {
+      competition_code: 'BRICS2026-ST-027',
+    }, {});
+  },
+};