feat: 优化联系邮箱编辑体验并展示本人注册邮箱

- 联系邮箱输入框支持清空（allowClear），并补充说明文字区分"注册邮箱"
- 用户主页对本人也展示注册邮箱条目（后端权限已同步放开）

Author: CodFrm

public/locales/zh-CN/translations.json

@@ -1624,6 +1624,7 @@
     "avatar_upload_success": "头像上传成功！",
     "cancel": "取消",
     "change_avatar": "更换头像",
+    "contact_email": "联系邮箱",
     "description": "个人简介",
     "description_max_length": "个人简介不能超过200个字符",
     "description_placeholder": "介绍一下自己吧...",
@@ -1632,6 +1633,7 @@
     "email_code_required": "请先发送并填写邮箱验证码",
     "email_code_resend": "重新发送",
     "email_code_sent": "验证码已发送",
+    "email_help_text": "用于公开展示以便他人联系您，与注册邮箱不同，可留空",
     "email_max_length": "邮箱地址不能超过50个字符",
     "email_placeholder": "联系邮箱",
     "email_send_code": "发送验证码",

src/components/UserProfile/UserEditModal.tsx

@@ -228,14 +228,20 @@ export default function UserEditModal({
         </Form.Item>
 
         <Form.Item
-          label="Email"
+          label={t('contact_email')}
           name="email"
           rules={[
             { type: 'email', message: t('email_validation') },
             { max: 50, message: t('email_max_length') },
           ]}
+          extra={
+            <Text type="secondary" className="text-xs">
+              {t('email_help_text')}
+            </Text>
+          }
         >
           <Input
+            allowClear
             prefix={<MailOutlined />}
             placeholder={t('email_placeholder')}
             maxLength={50}

src/components/UserProfile/UserProfileLayout.tsx

@@ -459,7 +459,7 @@ export default function UserProfileLayout({
                             },
                           ]
                         : []),
-                      ...(isAdmin && currentUserData.register_email
+                      ...(currentUserData.register_email
                         ? [
                             {
                               key: 'register_email',