fix(control-plane): keep the memories search open when the query is cleared (#3697)

The Memories view decided "is this bank empty?" from the filters the user
had *typed*, while `data` reflected the filters last sent to the server.
The text search only reaches the API on Enter, so after a search that
matched nothing, backspacing to an empty box flipped the filter check to
false while the zero-result response was still on screen — and that branch
replaces the entire view, search box included. The result was a bank full
of memories reporting "No memories yet", with re-navigating from Home as
the only way back.

Record the filters that actually produced the rows on screen and gate the
empty state (and the matching/showing/total labels) on those instead, so
they always describe what is rendered. Clearing the box now also re-runs
the query unfiltered, so the full list and its total come straight back
without needing another Enter.

Fixes #3670