Mentions Tab Inconsistency on User Profile

### Current Behavior

The "Mentions" tab on user profile could be consistent with "Posts" and "Discussions" tabs.

Current Result: In the "Mentions" tab on user profile, the number of mentions is not displayed.

### Steps to Reproduce

1. Go to the forum
2. Log in to your account
3. Click on your avatar
4. Click "Profile"
5. Go to "Mentions" tab
6. No count is displayed in the tab

### Expected Behavior

The "Mentions" tab should show the number of mentions, consistent with other profile tabs.

### Screenshots


### Environment

- Flarum version: 1.8.7
- PHP version: 8.3.21
- Browser: Chrome - version 138.0.7204.184; Firefox - version 141.0

### Additional Context

According to the Flarum documentation, Flarum is "carefully designed to be consistent and intuitive across platforms, out-of-the-box". The inconsistency between profile tabs breaks this design principle.