move discover mounting and tab switching to concurrent rendering

src/pages/DiscoverPage.tsx

@@ -1,4 +1,4 @@
-import { useState } from 'react'
+import { useState, startTransition } from 'react'
 import { useHasTmdbKey } from '../hooks/use-external'
 import LazyMount from '../components/ui/LazyMount'
 import { usePreferencesStore } from '../stores/preferences-store'
@@ -150,7 +150,7 @@ export default function DiscoverPage() {
             subtitle="Top of each genre, missing from your shelves"
             tiles={genreTiles()}
             expanded={expanded}
-            onSelect={setExpanded}
+            onSelect={k => startTransition(() => setExpanded(k))}
           />
 
           {kind === 'movie' && (
@@ -160,7 +160,7 @@ export default function DiscoverPage() {
               subtitle="Top-rated cinema by original language"
               tiles={languageTiles()}
               expanded={expanded}
-              onSelect={setExpanded}
+              onSelect={k => startTransition(() => setExpanded(k))}
             />
           )}
 
@@ -171,7 +171,7 @@ export default function DiscoverPage() {
               subtitle="Films grouped by who made them"
               tiles={studioTiles()}
               expanded={expanded}
-              onSelect={setExpanded}
+              onSelect={k => startTransition(() => setExpanded(k))}
             />
           )}
 
@@ -182,7 +182,7 @@ export default function DiscoverPage() {
               subtitle="Shows grouped by where they air"
               tiles={networkTiles()}
               expanded={expanded}
-              onSelect={setExpanded}
+              onSelect={k => startTransition(() => setExpanded(k))}
             />
           )}
         </>