Clear Facet Filters block not rendering when using Query String URL processor

Problem/Motivation

The "Clear Facet Filters" block only renders when the facet source uses the Pretty Paths URL processor. When switched to the default Query String processor, the block returns empty and the "Clear filter(s)" link never appears — even when facets are actively applied.

Steps to reproduce

Add the "Clear Facet Filters" block to a Site Studio view page.
Configure the facet source to use the Query String URL processor (default).
Apply any facet filter on the search page.
Observe that the "Clear filter(s)" link does not appear.

Proposed resolution

Extend the block's build() method to detect the f query parameter used by the Query String processor, and render a clear link that strips the f parameter while preserving other query params (e.g. keywords).

Remaining tasks

User interface changes

API changes

Data model changes