Server-backed filters need immediate transition feedback

Server-backed filters can be correct yet feel unresponsive when navigation triggers a full server render and the control shows neither optimistic selection nor pending state. Preserve server-side filtering, but update the selected control optimistically and expose transition feedback.

If warranted, isolate results behind a streaming or suspense boundary. First distinguish perceived dead time from dataset-size cost by comparing prefetched navigation and full-response timing; do not infer a large-data problem from a small visible result set.