Localization: "Add Custom Locale" window cannot be resized below 500×500 although it holds only two fields and one button

Steps to reproduce:

1. Create a new project
2. Install the Localization package (com.unity.localization)
3. Open Edit > Project Settings > Localization and click "Create" to make the settings asset
4. Click "Add Custom Locale"
5. Drag the window's corner to make it smaller

Actual results: The window stops at 500×500 and cannot be made smaller. Its content is a name field, a Locale Identifier field, and the "Create Locale" button, so most of the window is space

Expected results: The minimum size matches the content, so the window can be sized down to fit the two fields and the button

Reproducible with versions: 1.5.12 (6000.5.7f1, 6000.6.0f1, 6000.7.0a6)

Tested on (OS): MacBook Pro - Tahoe 26.6.2