Advance existing requests from Interactive Search

Pass requestId and requestedByUserId through request list and card components and into AudiobookDetailsModal. Add ADVANCEABLE_FROM_INTERACTIVE_SEARCH constant and logic so the Interactive Search modal routes to /api/requests/[id]/select-torrent for own/admin advanceable requests instead of creating a new request. Fix download-token usage to use the in-flight request id, extend Audiobook type with requestedByUserId, and add tests covering advance-vs-create routing and select-torrent behavior.

src/components/audiobooks/AudiobookCard.tsx

@@ -273,6 +273,8 @@ export function AudiobookCard({
         requestStatus={displayAudiobook.requestStatus}
         isAvailable={audiobook.isAvailable}
         requestedByUsername={audiobook.requestedByUsername}
+        requestId={audiobook.requestId}
+        requestedByUserId={audiobook.requestedByUserId}
         hasReportedIssue={audiobook.hasReportedIssue}
       />
     </>