Adding radius to macOS icons (#31)

### Before
<img width="239" height="125" alt="Screenshot 2025-08-26 at 3 36 21 PM"
src="https://github.com/user-attachments/assets/0f4efed4-919d-4af3-971b-e66b4dc67289"
/>

### After
<img width="206" height="158" alt="Screenshot 2025-08-26 at 3 58 30 PM"
src="https://github.com/user-attachments/assets/dc93bcff-4c04-4a42-96f3-bc828a059c0f"
/>

Note that in macOS Tahoe (26) looks like these will be masked similar to
iOS/iPadOS.

Author: mattherzog