Sprite Editor's Editing modes can be changed when the Sprite is in Read-only mode

How to reproduce:
1. Create a new URP 2D project
2. In the Hierarchy, right-click -> 2D Object -> Sprites -> Square
3. Select the created GameObject
4. In the Inspector, click "Open Sprite Editor" under the Sprite Renderer Component
5. Observe the results

Expected results: Sprite Editor Editing modes dropdown is grayed out because the Sprite is not editable
Actual results: Sprite Editor Editing modes can be switched, which has no point and leads to the visual problems

Reproducible with: 6000.0.65f1, 6000.3.3f1, 6000.4.0b3, 6000.5.0a3

Reproducible on: macOS Tahoe 26
Not reproducible on: No other environment tested