Focus indicators not visible on interactive elements

### Current Behavior

Some interactive elements do not display a visible focus indicator during keyboard navigation.

Elements such as the navbar toggle button, sidebar navigation items, and sidebar minimizer receive focus when using the Tab key, but no visible outline or highlight is shown.

### Steps to Reproduce

1. Open the application and navigate to the dashboard.
2. Press the Tab key repeatedly to move through interactive elements.
3. Observe that certain elements receive focus without displaying any visible indicator.

### Expected Behavior

All interactive elements should display a clear and visible focus indicator when they receive keyboard focus.

This allows users to easily track navigation when using the keyboard.

### Dependency-Track Frontend Version

4.x

### Browser

Microsoft Edge

### Browser Version

149.0.4022.62 (Official build) (64-bit)

### Operating System

Windows

### Checklist

- [x] I have read and understand the [contributing guidelines](https://github.com/DependencyTrack/dependency-track/blob/main/CONTRIBUTING.md#filing-issues)
- [x] I have checked the [existing issues](https://github.com/DependencyTrack/frontend/issues) for whether this defect was already reported

Reproduce the issue on the dashboard by navigating with the Tab key, then inspect the navbar toggle button, sidebar navigation items, and sidebar minimizer for their focus styles. Done means every interactive element in the reported areas has a clear visible focus indicator during keyboard navigation.

Written by the indexing model from the issue text.