Update Sorting Behavior for Search by Author and Search by Source

[kouloumos]

Currently, Bitcoin Search allows users to search by Author or Source via the quick options menu on the landing page, which offers hardcoded options.

When users click one of these options, the results are sorted by "Relevance" by default. However, this sorting option does not apply when there is no search query.

This issue addresses the sorting behavior when no search query is present. Instead of "Relevance," we should only allow ascending or descending order. I suggest defaulting to "desc" (Recent first) to show the most recent results at the top.

This functionality will also be useful for the upcoming Bitcoin Transcripts search page.