fix(plex): address S6 code-review — 5 findings

1. (correctness) Show hero rating regression: PlexBrowse's show hero rendered a
   rating only when show.imdb_rating was set, so after the S6 IMDb-only change a
   show with no imdb:// entry showed no rating. Now falls back to the audience
   `rating` like PlexInfo.
2. (correctness) ratingMin column mismatch: the rating filter and the /facets
   rating_max now key off coalesce(imdb_rating, rating) — the SAME "best score"
   the badge displays — so a ratingMin picked from a shown IMDb score narrows the
   right column instead of the raw audience `rating`.
3. (altitude) HU search gap: new query.vector_match() matches EITHER vector in HU
   (or_(search_vector_hu, search_vector)) so a row with no HU twin stays findable
   by its English title; ranking still uses the HU vector. field_recheck unions
   the HU+EN per-field tsvectors in HU, staying a strict subset of the prefilter.
4. (test-coverage) Extracted the badge logic to lib/plexRating.pickRatingBadge
   (shared by PlexInfo + the show hero) with a unit test (imdb-preferred, audience
   fallback, 0-score, none). Backend tests added for the HU union search + the
   IMDb-preferred rating filter.
5. (efficiency) Language switch no longer double-fetches the grid: browseQ is
   gated on a committedLang state that lags `lang` by one render, so the
   genre-clear effect settles into a single fetch instead of one throwaway fetch
   with stale-language genres plus a second.

DB-lane suite 295 passed / 2 skip; FE tsc/knip/lint clean, 217 vitest pass.

frontend/src/components/PlexBrowse.tsx

@@ -16,6 +16,7 @@ import { createPortal } from "react-dom";
 import { useTranslation } from "react-i18next";
 import type { TFunction } from "i18next";
 import { plexLang } from "../i18n";
+import { pickRatingBadge } from "../lib/plexRating";
 import {
   useInfiniteQuery,
   useQuery,
@@ -121,6 +122,9 @@ export default function PlexBrowse() {
   // Active language for the HU overlay: "hu" serves Hungarian metadata, else EN. In the query keys so
   // a switch refetches the grid/facets/detail; useTranslation re-renders this component on switch.
   const lang = plexLang();
+  // The language the grid query is allowed to run at — lags `lang` by one render on a switch so the
+  // genre-clear effect (below) can settle first (see the effect for why).
+  const [committedLang, setCommittedLang] = useState(lang);
   // Plex's active-filter chip row (above the grid), the shared feed idiom: one removable chip per
   // narrowing, plus a Clear-all (shared with the sidebar) that resets filters + watch-state + sort.
   const plexChips = usePlexActiveFilters();
@@ -196,7 +200,9 @@ export default function PlexBrowse() {
 
   const browseQ = useInfiniteQuery({
     queryKey: qk.plexLibrary(scope, dq, sortState, show, filters, fieldState, lang),
-    enabled: !!scope && sub.view.kind === "grid",
+    // Gate on committedLang so a language switch fires ONE fetch (after the genre-clear effect
+    // settles), not a throwaway one with stale-language genres followed by a second.
+    enabled: !!scope && sub.view.kind === "grid" && committedLang === lang,
     initialPageParam: 0,
     queryFn: ({ pageParam }) =>
       api.plexLibrary({
@@ -218,14 +224,15 @@ export default function PlexBrowse() {
 
   // Genre chips are language-specific strings (the HU column stores "Dráma", the EN one "Drama"), so a
   // selection made in one language matches nothing against the other's column and would silently empty
-  // the grid. Drop the genre selection when the language flips (only on an actual change, not mount).
-  const prevLangRef = useRef(lang);
+  // the grid. On a language flip, drop the genre selection — and gate the grid query on the language
+  // being "committed" (below) so we don't fire one throwaway fetch with the stale-language genres and
+  // then a second after the clear; the query waits for both to settle into a single fetch.
   useEffect(() => {
-    if (prevLangRef.current !== lang) {
-      prevLangRef.current = lang;
+    if (committedLang !== lang) {
+      setCommittedLang(lang);
       if (filters.genres.length) setFilters({ ...filters, genres: [] });
     }
-  }, [lang, filters, setFilters]);
+  }, [lang, committedLang, filters, setFilters]);
 
   const items = browseQ.data?.pages.flatMap((p) => p.items) ?? [];
   const total = browseQ.data?.pages[0]?.total ?? 0;
@@ -1413,20 +1420,26 @@ function PlexShowView({
               {show.season_count != null && (
                 <span>· {t("plex.seasons", { count: show.season_count })}</span>
               )}
-              {show.imdb_rating != null && (
-                <button
-                  onClick={
-                    onFilter
-                      ? () => onFilter({ ratingMin: Math.floor(show.imdb_rating!) })
-                      : undefined
-                  }
-                  className={`inline-flex items-center gap-1 ${onFilter ? "cursor-pointer hover:text-accent" : "cursor-default"}`}
-                >
-                  {/* decorative rating gold — intentionally NOT a status token */}
-                  · <Star className="w-3.5 h-3.5 text-amber-400" fill="currentColor" />
-                  {show.imdb_rating}
-                </button>
-              )}
+              {(() => {
+                // IMDb score when present, else the Plex audience score — mirrors PlexInfo so a show
+                // with no imdb:// entry (imdb_rating NULL after the S6 IMDb-only change) still shows a
+                // rating instead of dropping the badge entirely.
+                const badge = pickRatingBadge(show.imdb_rating, show.rating);
+                if (!badge) return null;
+                const { score } = badge;
+                return (
+                  <button
+                    onClick={
+                      onFilter ? () => onFilter({ ratingMin: Math.floor(score) }) : undefined
+                    }
+                    className={`inline-flex items-center gap-1 ${onFilter ? "cursor-pointer hover:text-accent" : "cursor-default"}`}
+                  >
+                    {/* decorative rating gold — intentionally NOT a status token */}
+                    · <Star className="w-3.5 h-3.5 text-amber-400" fill="currentColor" />
+                    {score.toFixed(1)}
+                  </button>
+                );
+              })()}
             </div>
             {show.genres.length > 0 && (
               <div className="mt-2 flex flex-wrap gap-1.5">

frontend/src/components/PlexInfo.tsx

@@ -5,6 +5,7 @@ import { useQueryClient } from "@tanstack/react-query";
 import { Check, ExternalLink, FolderPlus, ListPlus, Play, RotateCcw, Star, X } from "lucide-react";
 import { api, type PlexFilters, type PlexItemDetail } from "../lib/api";
 import { formatRuntime } from "../lib/format";
+import { pickRatingBadge } from "../lib/plexRating";
 import { notifyActionError } from "../lib/actionErrors";
 import {
   DetailCustomizeMenu,
@@ -198,9 +199,9 @@ export default function PlexInfo({
                 {(() => {
                   // IMDb score when we have one (with the IMDb link); otherwise the Plex audience
                   // score (no IMDb link/branding, so a non-IMDb score is never mislabelled as IMDb).
-                  const score = detail.imdb_rating ?? detail.rating;
-                  if (score == null) return null;
-                  const isImdb = detail.imdb_rating != null;
+                  const badge = pickRatingBadge(detail.imdb_rating, detail.rating);
+                  if (!badge) return null;
+                  const { score, isImdb } = badge;
                   return (
                     // decorative rating gold — intentionally NOT a status token
                     <span className="inline-flex items-center gap-1 rounded-md bg-amber-400/15 px-1.5 py-0.5 font-semibold text-amber-500">