fix(ui): a page's sub-tab is remembered per browser tab, not forever

Settings, Configuration, Statistics and Users kept the last sub-tab in localStorage, so every
fresh tab opened Configuration on "Plex" as if that were its home. useTabPersistedState keeps it
in sessionStorage (account-scoped): a reload and a trip to another page keep it, a new tab starts
on the first sub-tab. The pre-selects (a Review link, the Google-link return) write the same store;
a value an older build left in localStorage is cleared on first read.

frontend/src/components/ConfigPanel.tsx

@@ -15,7 +15,7 @@ import { Switch } from "./ui/form";
 import SegmentedToggle from "./ui/SegmentedToggle";
 import FilterSelect from "./ui/FilterSelect";
 import { DraftSaveBar, type SaveState } from "./ui/DraftSaveBar";
-import { LS, useAccountPersistedState } from "../lib/storage";
+import { LS, useTabPersistedState } from "../lib/storage";
 import { notifyActionError } from "../lib/actionErrors";
 import { Button } from "./ui/Button";
 import { CheckRow } from "./ui/NativeControls";
@@ -56,7 +56,7 @@ export default function ConfigPanel() {
   const [reseedToken, setReseedToken] = useState(0);
   // One tab per config group (persisted). Called before the loading guard so hook order is
   // stable; the active id is clamped to a real group at render time once data has loaded.
-  const [tab, setTab] = useAccountPersistedState(LS.configTab);
+  const [tab, setTab] = useTabPersistedState(LS.configTab);
 
   // A stable signature of the config SHAPE — changes only when keys are added/removed, not when an
   // unchanged refetch produces a new baseline object. Re-seed the draft on a shape change (initial