feat: Hide the toolbar text; function descriptions appear when hovering over the icons.

### Preflight checklist

- [x] I searched [existing issues](https://github.com/ja7ad/hydra/issues?q=is%3Aissue) and this has not been proposed already.
- [x] I checked the [README](https://github.com/ja7ad/hydra/blob/main/README.md) and this is not already supported.

### Component

CLI (`hydra`)

### Problem

Hide the toolbar text; function descriptions appear when hovering over the icons.

### Proposed solution

Hide the toolbar text; function descriptions appear when hovering over the icons.

### Alternatives considered

_No response_

### Platforms this should cover

- [ ] Linux
- [ ] macOS
- [ ] Windows
- [ ] Android / iOS (via `libhydra`)

### Additional context

### Compatibility

- [ ] This changes existing behavior (flags, defaults, output format, or the C ABI).

### Contribution

- [ ] I'm willing to open a pull request implementing this.

Start by running the hydra CLI and locating the toolbar and icon-rendering entry points in the Rust codebase. Verify the current toolbar labels and hover behavior, then confirm that the completed change hides the text while showing each function description on icon hover.

Written by the indexing model from the issue text.