fix a markup bug with multiple aria-current attr have page values

[masao]

Summary

Fix the breadcrumb markup so that aria-current="page" is applied only to the current page item.

Previously, multiple breadcrumb items were marked with aria-current="page", resulting in invalid or misleading accessibility markup. This change ensures that only the active breadcrumb item is identified as the current page.

A regression test has also been added to verify that each breadcrumb contains exactly one element with aria-current="page".

Types of changes

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• Documentation or other updates (if none of the other choices apply)