chore: rebrand product as 省心推 and lock UI to zh-CN

Update server titles, web/desktop window/tray/document titles, login
copy, and electron build metadata to use the Chinese product name 省心推.
Drop the runtime locale switcher and en-US import — the app now ships
zh-CN only.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/admin-web/src/i18n/messages/zh-CN.ts

@@ -1,7 +1,7 @@
 const zhCN = {
   app: {
-    name: "GEO工具平台",
-    loginIntro: "面向企业的品牌资产管理与内容生产协作系统",
+    name: "省心推",
+    loginIntro: "面向企业和个人的品牌资产管理与内容生产协作系统",
   },
   locale: {
     "zh-CN": "中文简体",
@@ -153,7 +153,7 @@ const zhCN = {
   route: {
     login: {
       title: "欢迎回来",
-      description: "使用真实租户账号登录 GEO 工具平台。",
+      description: "登录省心推，开启品牌内容创作之旅",
     },
     workspace: {
       title: "工作台",