feat: 增强用户管理功能，添加用户名、微信号和备注字段

- 新增User模型字段：username（用户名）、wechat（微信号）、notes（备注）
- 扩展用户搜索功能，支持通过用户名和微信号搜索
- 添加用户个人资料更新功能，用户可自行编辑用户名和微信号
- 管理员用户列表新增用户名、微信号、备注显示列
- 备注字段仅对管理员可见，增强数据安全性
- 完善中英文国际化翻译
- 修复国际化文件中重复属性的TypeScript错误

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

frontend/src/i18n/locales/en.ts

@@ -335,6 +335,15 @@ export default {
     memberSince: 'Member Since',
     administrator: 'Administrator',
     user: 'User',
+    username: 'Username',
+    wechat: 'WeChat ID',
+    enterUsername: 'Enter username',
+    enterWechat: 'Enter WeChat ID',
+    editProfile: 'Edit Profile',
+    updateProfile: 'Update Profile',
+    updating: 'Updating...',
+    updateSuccess: 'Profile updated successfully',
+    updateFailed: 'Failed to update profile',
     changePassword: 'Change Password',
     currentPassword: 'Current Password',
     newPassword: 'New Password',
@@ -446,8 +455,28 @@ export default {
       admin: 'Admin',
       user: 'User',
       disabled: 'Disabled',
+      email: 'Email',
+      password: 'Password',
+      username: 'Username',
+      wechat: 'WeChat ID',
+      notes: 'Notes',
+      enterEmail: 'Enter email',
+      enterPassword: 'Enter password',
+      enterUsername: 'Enter username (optional)',
+      enterWechat: 'Enter WeChat ID (optional)',
+      enterNotes: 'Enter notes (admin only)',
+      notesHint: 'This note is only visible to administrators',
+      enterNewPassword: 'Enter new password (optional)',
+      leaveEmptyToKeep: 'Leave empty to keep current password',
+      generatePassword: 'Generate random password',
+      copyPassword: 'Copy password',
+      creating: 'Creating...',
+      updating: 'Updating...',
       columns: {
         user: 'User',
+        username: 'Username',
+        wechat: 'WeChat ID',
+        notes: 'Notes',
         role: 'Role',
         subscriptions: 'Subscriptions',
         balance: 'Balance',
@@ -471,16 +500,6 @@ export default {
       none: 'None',
       noUsersYet: 'No users yet',
       createFirstUser: 'Create your first user to get started.',
-      email: 'Email',
-      password: 'Password',
-      enterEmail: 'Enter email',
-      enterPassword: 'Enter password',
-      enterNewPassword: 'Enter new password (optional)',
-      leaveEmptyToKeep: 'Leave empty to keep current password',
-      generatePassword: 'Generate random password',
-      copyPassword: 'Copy password',
-      creating: 'Creating...',
-      updating: 'Updating...',
       userCreated: 'User created successfully',
       userUpdated: 'User updated successfully',
       userDeleted: 'User deleted successfully',