How to reproduce:
1. Create a new Unity project
2. Go to Window -> Package Manager and install the Localization package
3. Open Library/PackageCache/com.unity.localization@<version> in a file browser with hidden files shown
4. Observe the results
Expected results: Only shippable package content is present
Actual results: ".npmignore" is present inside the installed package
Reproducible with: 6000.7.0a6
Reproducible on: macOS Tahoe 26 (M1)
Not reproducible on: No other environment tested