🌐 feat(system-settings): add ServerAddress option & full i18n support

This commit brings System Settings in line with Payment Settings and
prepares the whole component for multi-language deployments.

Key points
----------
• Introduced a “General Settings” card in `SystemSetting.js`
  - Adds a `ServerAddress` field (copied from Payment Settings).
  - Explains that this URL is used for payment callback & default homepage.
  - Implements `submitServerAddress` to persist the option.

• Internationalisation
  - Imported `useTranslation` and wrapped **all** Chinese UI strings in `t()`.
  - Localised section titles, labels, placeholders, banners, buttons,
    modal texts and toast messages.
  - Dynamic banner/tool-tip descriptions now combine `t()` fragments with
    template literals for runtime URLs.

• UX improvements
  - Added contextual `extraText` under the ServerAddress input.
  - Ensured placeholders like “sensitive info…” are translatable.

With these changes, administrators can configure the server URL from the
System Settings tab, and the entire page is ready for seamless language
switching via the existing i18n framework.

web/src/i18n/locales/en.json

@@ -1756,5 +1756,6 @@
   "生成数量必须大于0": "Generation quantity must be greater than 0",
   "创建后可在编辑渠道时获取上游模型列表": "After creation, you can get the upstream model list when editing the channel",
   "可用端点类型": "Supported endpoint types",
-  "未登录，使用默认分组倍率：": "Not logged in, using default group ratio: "
+  "未登录，使用默认分组倍率：": "Not logged in, using default group ratio: ",
+  "该服务器地址将影响支付回调地址以及默认首页展示的地址，请确保正确配置": "This server address will affect the payment callback address and the address displayed on the default homepage, please ensure correct configuration"
 }