Scroll trail results to the top whenever filters change

[NicooleT]

Problem

When the user changes the selected regions or switches the Name / Distance / Rating filter, the trail results update but keep the previous scroll position. This can leave the user partway down a newly filtered or reordered list, requiring a manual scroll back to the top.

Expected behavior

Reset the trail results list to the top every time either the region selection or the Name / Distance / Rating selection changes.

Acceptance criteria

• Selecting or deselecting a region returns the results list to the top.
• Switching between Name, Distance, and Rating returns the results list to the top.
• The behavior works from any existing scroll position.
• The top item shown belongs to the newly filtered or reordered results.