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/App.vue

@@ -1,18 +1,12 @@
 <script setup lang="ts">
-import enUS from "ant-design-vue/es/locale/en_US";
 import zhCN from "ant-design-vue/es/locale/zh_CN";
-import { computed } from "vue";
-import { useI18n } from "vue-i18n";
 
 import ImageUploadProgressOverlay from "@/components/ImageUploadProgressOverlay.vue";
-
-const { locale } = useI18n();
-const antLocale = computed(() => (locale.value === "en-US" ? enUS : zhCN));
 </script>
 
 <template>
   <a-config-provider
-    :locale="antLocale"
+    :locale="zhCN"
     :theme="{
       token: {
         colorPrimary: '#1677ff',