feedback6: version 0.2.1 — package.json / package-lock.json / APP_VERSION (DEV_BUILD turns false: the title-screen dev tag, the boot warning and the package guard go)

- CHANGELOG 0.2.1 (2026-10-07): the streams' lines collected (新功能: the update package and MANIFEST.json; 规则（按官方）:
  联防 on the round's battlefield, 突袭 onto a teammate's half, full potential, the replace dialog for consumables,
  the 外勤医疗 Touch, 凋亡, 贾维's 拉普兰德, the 频次 器物 / leader summons; 界面: the collapse arrow, 自选 picks in the bond
  lists, flyers, enemy animations, the Touch card, Esc in the 自选 picker; 联机与大厅: battle messages while a battle
  loads; 工具与开发: the update build, .gitignore), one intro paragraph.
- README: the dev warning under the title removed, the release badge, 「当前版本 0.2.1」; DESIGN's version line names
  0.2.1 (§26) as the state described; §26's intro says when the dev line shipped.
- Tests: version, docs-consistency, docs-paths, package, i18n-packs, update-package, update-boot 80 / 80.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "stronghold-protocol-alliance",
-  "version": "0.2.1-dev",
+  "version": "0.2.1",
   "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",