fix(design): the table header takes the B9 fade utility, and every size is dvh, not vh (E28 S3d4)

The table header carried an arbitrary-value copy of fade-below; a contract refuses a hand gradient of a surface colour. 100vh is the viewport with a tablet browser's toolbar retracted, so h-screen / min-h-screen / static vh hid the last rows under it; a contract holds dvh (the Plex player stage changes with S3f, where it is played on the tablet).

frontend/src/components/PlexSearchBox.tsx

@@ -141,7 +141,7 @@ export default function PlexSearchBox() {
             id={listId}
             role="listbox"
             aria-label={t("plex.suggest.aria")}
-            className={`${SURFACE.menu} absolute left-0 right-0 top-full z-menu mt-2 max-h-[70vh] overflow-y-auto animate-[popIn_0.16s_ease]`}
+            className={`${SURFACE.menu} absolute left-0 right-0 top-full z-menu mt-2 max-h-[70dvh] overflow-y-auto animate-[popIn_0.16s_ease]`}
           >
             {suggestions.length === 0 && suggestQ.isFetching && (
               <div className="px-3 py-2 text-sm text-muted">{t("plex.loading")}</div>