Update getNavigationBadge() to allow int|string|null return type

[iRaziul]

Description

Updated getNavigationBadge method to support multiple return types.
The method can now return int, string, or null instead of only string|null.
This allows more flexibility for navigation badges that might need to display numeric values or whenever using strict types.

Visual changes

No visual changes - this is a type declaration update that doesn't affect runtime behavior.

Functional changes

• Code style has been fixed by running the composer cs command
• Changes have been tested to not break existing functionality
• Documentation is up-to-date (assuming method docs were updated if needed)