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/lib/queryKeys.ts

@@ -123,10 +123,11 @@ export const qk = {
   // refetches it alone.
   plexDiscover: (...rest: unknown[]) => ["plex-discover", ...rest],
   // Variadic like plexDiscover so it can key by scope + lang + the active filters (lang because a genre
-  // filter narrows against the language-specific genre column, like the grid). The ↻ reshuffle is the
-  // query's own refetch, and nothing invalidates this key — deliberately: a watched toggle flips the
-  // card in place (and reverts it on a failure) rather than reshuffle the rail under the viewer.
-  plexSurprise: (...rest: unknown[]) => ["plex-surprise", ...rest],
+  // filter narrows against the language-specific genre column, like the grid). UNDER the discover root,
+  // so whatever refreshes the rails (a watched toggle, a player closing) refreshes this one too: its
+  // refetch reads the same draw again (`keep`), and only the ↻ deals a new one. As a sibling root the
+  // draw's cards kept the watch state they were drawn with.
+  plexSurprise: (...rest: unknown[]) => ["plex-discover", "surprise", ...rest],
   plexSuggest: (...rest: unknown[]) => ["plex-suggest", ...rest],
   // Optional trailing `lang`: a language switch remounts the detail with a new key so HU/EN
   // metadata is cached separately. Omitting it (e.g. for a prefix invalidation) still matches both.