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。

.gitignore

@@ -0,0 +1,48 @@
+# Dependencies
+node_modules/
+
+# Build output
+dist/
+dist-ssr/
+
+# Logs
+logs/
+*.log
+npm-debug.log*
+yarn-debug.log*
+yarn-error.log*
+pnpm-debug.log*
+
+# Runtime (egg)
+run/
+.wb_*/
+.wb_check_state.js
+.egg-config.json
+
+# Env / secrets (defense-in-depth; real .env.production lives outside this repo)
+.env*
+!.env.example
+
+# Coverage / cache
+coverage/
+.cache/
+
+# Agent / tooling state
+.workbuddy/
+
+# Editor
+.vscode/*
+!.vscode/extensions.json
+.idea
+.DS_Store
+
+# Uploaded / runtime data under app/public (keep templates as source)
+app/public/uploads/
+app/public/answers/
+app/public/works/
+app/public/materials/
+app/public/news/
+app/public/carousel/
+app/public/tmp/
+app/public/exports/
+test_dir/