Traffic graph shows truncated date ("Mar...") on 90-day timeframe in SK dashboard

## Bug Description

On the SK dashboard, more specifically on the traffic graph:
- When I switch to 90 day timeframe, the graph would show 'Mar...'
- It just feels odd as all the other timeframes have a proper date.

## Steps to reproduce

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

## Screenshots

## Additional Context

- PHP Version:
- OS: [e.g. iOS]
- Browser: [e.g. chrome, safari]
- Plugin Version: [e.g. 22]
- Device: [e.g. iPhone6]

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## Acceptance criteria

*

## Implementation Brief

* [ ]

### Test Coverage

*

## QA Brief

*

## Changelog entry

*

The issue names no files or tests. Start by locating the SK dashboard traffic graph and the date-label formatting used when the 90-day timeframe is selected; reproduce the truncated "Mar..." label and trace the relevant frontend entry point. Done means the 90-day graph displays a complete, consistent date like the other timeframes.

Written by the indexing model from the issue text.