💄refactor: enhance EditUser and AddUser form validation & UX

Changes in `web/src/pages/User/EditUser.js`:
• Added `rules` to
  – `Form.Select group`: now required with error “Please select group”.
  – `Form.InputNumber quota`: now required with error “Please enter quota”.
• Added `step={500000}` to quota `InputNumber` for quicker numeric input.
• Replaced invalid `readonly` with React-correct `readOnly`, and added descriptive placeholders for all binding-info fields (GitHub/OIDC/WeChat/Email/Telegram).
• Removed unused `downloadTextAsFile` import.

These updates tighten form validation, improve data entry ergonomics, and restore clear read-only indicators for third-party bindings.

web/src/i18n/locales/en.json

@@ -471,10 +471,11 @@
   "请输入新的密码": "Please enter a new password",
   "显示名称": "Display Name",
   "请输入新的显示名称": "Please enter a new display name",
-  "已绑定的 GitHub 账户": "GitHub Account Bound",
-  "此项只读，要用户通过个人设置页面的相关绑<EFBFBD><EFBFBD>按钮进<EFBFBD><EFBFBD>绑<EFBFBD><EFBFBD><EFBFBD>，不可直接修改": "This item is read-only. Users need to bind through the relevant binding button on the personal settings page, and cannot be modified directly",
-  "已绑定的微信账户": "WeChat Account Bound",
-  "已绑定的邮箱账户": "Email Account Bound",
+  "已绑定的 GITHUB 账户": "Bound GitHub Account",
+  "已绑定的 WECHAT 账户": "Bound WeChat Account",
+  "已绑定的 EMAIL 账户": "Bound Email Account",
+  "已绑定的 TELEGRAM 账户": "Bound Telegram Account",
+  "此项只读，要用户通过个人设置页面的相关绑定按钮进行绑定，不可直接修改": "This item is read-only. Users need to bind through the relevant binding button on the personal settings page, and cannot be modified directly",
   "用户信息更新成功！": "User information updated successfully!",
   "使用明细（总消耗额度：{renderQuota(stat.quota)}）": "Usage Details (Total Consumption Quota: {renderQuota(stat.quota)})",
   "用户名称": "User Name",