[Bug]: Fixed width buttons break focus styling

### Code of conduct

- [x] I agree to follow this project's code of conduct.

### Impacted component(s)

sp-button

### Expected behavior

Should be able to create a fixed width button with a long label which truncates without breaking the keyboard focus ring.

### Actual behavior

Creating a fixed width button with overflow:hidden breaks the focus ring.

### Screenshots

_No response_

### What browsers are you seeing the problem in?

Chrome, Firefox, Safari, Microsoft Edge

### How can we reproduce this issue?

1. Go to https://studio.webcomponents.dev/edit/8zDzFboByFRPg81avRUF/src/index.ts?p=stories
2. keyboard focus on the first button with overflow:hidden;
4. Note there is no focus ring
5. tab to the 2nd button without overflow:hidden
6. Note there is a focus ring

### Sample code or abstract reproduction which illustrates the problem

_No response_

### Severity

None

### Logs taken while reproducing problem

_No response_

Start with the sp-button component and reproduce the behavior using the linked studio example at src/index.ts. Compare keyboard focus on the fixed-width button with overflow:hidden against the second button, then verify that a long label truncates while the focus ring remains visible in Chrome, Firefox, Safari, and Edge.

Written by the indexing model from the issue text.