Variant filter selection on PDP remains active when filters are changed

The variant filtering functionality on the PDP in the webshop has been improved.
When a user changes a child filter (such as size), the previously selected parent filter (such as color) is now retained.

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If the selected combination doesn’t exist, the system automatically falls back to the default variant or removes the selection — with a clear notification shown to the user.

This results in a more predictable and user-friendly shopping experience for customers.