feedback6: version 0.2.1-dev — 0.2.0 is released; the dev line is marked as before (README warning under the title, an orange dev badge, the 开发版 tag on the title screen, the boot-banner warning, the package guard: DEV_BUILD from the version)

package.json

@@ -1,6 +1,6 @@
 {
   "name": "stronghold-protocol-alliance",
-  "version": "0.2.0",
+  "version": "0.2.1-dev",
   "private": true,
   "description": "明日方舟「卫戍协议：盟约」非官方同人联机网页复刻（1–4 人合作，Node.js 服务器 + 浏览器客户端）",
   "license": "GPL-3.0-or-later",