fix(plex): Restart only where an episode has a resume point; the Surprise draw is re-read, not redrawn

Show cards carry resumable (ShowState, from the same rollup) so a part-watched
show whose next episode is untouched offers Play, not a Continue and a Restart
that do the same thing; plexStarted is the one rule for cards and menus. The
Surprise rail's key sits under the discover root: whatever refreshes the rails
re-reads the draw (keep=) with its watch state now, kept past the 5-minute gc,
and only the reshuffle deals. Closing the player refreshes the Discover rails.
A show card's play acts on the last click only, and only where it was made.

frontend/src/components/PlexDiscover.tsx

@@ -1,4 +1,4 @@
-import { type ReactNode } from "react";
+import { useRef, type ReactNode } from "react";
 import { useTranslation } from "react-i18next";
 import { useQuery, useQueryClient } from "@tanstack/react-query";
 import { RotateCcw } from "lucide-react";
@@ -120,25 +120,36 @@ export default function PlexDiscover({
     queryFn: () => api.plexDiscover(scope, lang, filters),
   });
   // Surprise-me is its own query so the ↻ button can redraw it without refetching the whole surface.
-  // A redraw hands over the draw on screen, so a small filtered pool deals its other titles first.
+  // A draw stands until the ↻ (or another scope, language or filter) asks for a new one: redrawn on
+  // every refetch, the card just looked at was gone from its rail on Back from the player or a show
+  // page. So a refetch reads the draw on screen again (`keep`: fresh watch state, same titles), and
+  // only the ↻ deals — handing over that draw, so a small filtered pool deals its other titles first.
   const surpriseKey = qk.plexSurprise(scope, lang, filters);
+  const redraw = useRef(false);
   const surpriseQ = useQuery({
     queryKey: surpriseKey,
     queryFn: () => {
-      const shown = qc.getQueryData<{ items: PlexCard[] }>(surpriseKey)?.items ?? [];
+      const shown = (qc.getQueryData<{ items: PlexCard[] }>(surpriseKey)?.items ?? []).map(
+        (c) => c.id,
+      );
+      const deal = redraw.current || shown.length === 0;
+      redraw.current = false;
       return api.plexSurprise(
         scope,
         undefined,
         filters,
         lang,
-        shown.map((c) => c.id),
+        deal ? { exclude: shown } : { keep: shown },
       );
     },
-    // A draw stands until ↻ (or another scope, language or filter) asks for a new one. A stale one was
-    // redrawn on every remount — Back from the player or a show page — and on a return to the window,
-    // so the card just looked at was gone from the rail it came from.
-    staleTime: Infinity,
+    // Kept past the default five minutes unobserved: a film watched from the rail outlasts that, and
+    // a collected draw is a new one.
+    gcTime: Infinity,
   });
+  const reshuffle = () => {
+    redraw.current = true;
+    void surpriseQ.refetch();
+  };
 
   // Watched toggle over BOTH this surface's cache (so a rail card flips instantly) and the surprise
   // list, then persist + resync via the shared helper — invalidating the grid too so it agrees.
@@ -243,7 +254,7 @@ export default function PlexDiscover({
           cards={surprise}
           action={
             <IconButton
-              onClick={() => surpriseQ.refetch()}
+              onClick={reshuffle}
               loading={surpriseQ.isFetching}
               label={t("plex.discover.reshuffle")}
             >