The Subi AI Copilot's 'No results found' card no longer stacks

When the Subi AI Copilot searched for something and found nothing, it drew a "No results found, try different filters" card. If the Copilot searched more than once within the same turn (for example, retrying with different criteria after an empty result) and still found nothing each time, the panel stacked one of those cards per search, so a single turn could show the same empty-result card two or three times in a row.

What's fixed: the empty-result card now renders once per conversation turn, carrying the criteria from the last search attempt, instead of once per search round within that turn.

This only affects how the empty-search state is displayed in the Copilot panel; the Copilot's search behavior, the queries it runs, and every other card type are unchanged.